What do the sepals protect in the flower bud?

Sepals serve a crucial protective role for the flower bud by shielding the developing petals and reproductive structures from environmental factors. Their primary function is to safeguard the flower during its early stages of growth, which includes protection from moisture such as rain. While they may also provide some level of defense against other elements like sunlight and wind, their most significant contribution is ensuring that the flower's internal components, which are sensitive to water and temperature extremes, remain safe until they are ready to bloom. Thus, the correct answer highlights their protective function against rain, ensuring the flower develops optimally.