In all plants, the major sites of photosynthesis are:

Explanation

The correct answer is 'Leaf'. In most plants, leaves are the primary sites for photosynthesis. They possess mesophyll cells filled with chloroplasts, which contain chlorophyll to capture sunlight and convert it into chemical energy. This process mainly occurs in the leaves because they are structured to maximize light absorption. Stems, roots, and branches, while essential for other functions such as support, transport, and nutrient absorption, do not have the necessary chloroplasts to perform photosynthesis effectively.