What is the primary process through which plants obtain energy?

Plants primarily obtain energy through photosynthesis, which is a vital process that occurs primarily in the chloroplasts of plant cells. During photosynthesis, plants convert light energy, typically from the sun, into chemical energy by using carbon dioxide and water as raw materials. This process not only produces glucose, which serves as an energy source for the plant, but it also releases oxygen as a byproduct, which is essential for the survival of most living organisms on earth.

In contrast, respiration is a process that occurs in both plants and animals, where glucose is broken down to release energy for cellular activities. Fermentation is an anaerobic process that can occur in the absence of oxygen, typically in yeast and some bacteria, and it is not the primary method by which plants acquire energy. Transpiration refers to the process of water vapor loss from plant surfaces, particularly through small openings called stomata, and is crucial for water regulation but unrelated to energy acquisition. Thus, photosynthesis is the correct answer as it encompasses the essential mechanism by which plants harness energy from sunlight.