A hypothesis is a proposed explanation based on limited evidence that can be further tested. The other options represent different levels of scientific conclusions that are not tentative testable explanations.

Solar energy is considered renewable because it is harnessed from the sun and naturally replenished. The other options are fossil fuels which are finite and non-renewable.

Cells are the smallest living units that make up all organisms and are the fundamental building blocks of life. The other options, while important in science, do not represent the basic unit of life.

Gravity is the force that attracts objects toward the Earth's center, causing them to fall. The other options do not have the universal effect of gravity on all matter.

Oxygen is vital for cellular respiration, enabling the production of energy in living organisms. The other gases do not support respiration in the way oxygen does.

Reactants are the substances that start a chemical reaction and change into new substances. The other terms refer to either the outcomes or other components of a reaction.

Increasing temperature raises the kinetic energy of molecules, leading to more frequent and effective collisions. This generally speeds up chemical reactions.

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to produce glucose and oxygen. The other processes do not involve the conversion of sunlight into chemical energy.

Enzymes serve as catalysts in biological reactions, speeding up the reactions without being used up. The other options do not correctly describe the function of enzymes.

Mars is nicknamed the Red Planet due to its reddish appearance, which is caused by iron oxide on its surface. The other planets have different characteristics and appearances.

The Sun is the major driving force behind Earth's weather, as its energy heats the atmosphere and leads to weather patterns. The other sources are not as significant in influencing weather.

An ecosystem is composed of living organisms and their interactions with the non-living components of their environment. The other options describe concepts not related to ecological communities.

Evaporation is the process in which water transitions from a liquid state to a gaseous state. The other terms describe different phase changes or processes related to water.

Buoyancy is mainly determined by an object's density compared to that of the surrounding fluid. The other factors have little to no effect on whether an object sinks or floats.

Nitrogen makes up approximately 78% of Earth's atmosphere, making it the most abundant gas. The other gases are present in significantly smaller amounts.

Newton's first law states that an object with zero net force will either remain at rest or move at a constant velocity. The other choices imply acceleration, which requires a net force.

Mitochondria are known as the powerhouse of the cell because they produce ATP through cellular respiration. The other organelles have different functions unrelated to ATP production.

Combustion reactions, particularly those involving hydrocarbons, generally produce carbon dioxide and water as products. The other substances are not typical products of a combustion reaction.

Uniformitarianism suggests that the processes observed today have been consistent over geological time. This means that current geological processes can be used to interpret the Earth's past, unlike the other options.

The blue color of the sky is primarily due to Rayleigh scattering, where shorter blue wavelengths of sunlight are scattered more than other colors by the atmosphere. The other options do not accurately account for the blue appearance of the sky.