Which of the following is a primary function of mesophyll cells in C4 plants?

Mesophyll cells in C4 plants are primarily responsible for collecting and fixing carbon dioxide. This process occurs in a specialized manner, where these cells actively participate in the initial stages of photosynthesis by capturing CO2 from the atmosphere. In C4 plants, the mesophyll cells facilitate a more efficient carbon fixation process compared to C3 plants, using a four-carbon compound as an intermediate before transferring the fixed carbon to bundle-sheath cells for further processing in photosynthesis. This adaptation helps C4 plants thrive in high-temperature and low-CO2 environments, enhancing their ability to photosynthesize efficiently. Therefore, the focal role of mesophyll cells in the context of C4 photosynthesis is to optimize carbon fixation, making option C the correct choice in this context.