Final answer:
The true statement is that plants need chlorophyll for photosynthesis, as it is essential for converting water and carbon dioxide into glucose and oxygen.
Step-by-step explanation:
The correct statement among the options provided is: a. Plants need chlorophyll for photosynthesis. This is true because chlorophyll is the pigment in plants that absorbs light energy from the sun, which is necessary for converting water and carbon dioxide into glucose and oxygen during the photosynthesis process. The other statements are incorrect because animals exhale carbon dioxide, not oxygen; female egg cells are found in the pistil, not the stamen; and pollination can occur in various seasons, not just winter.