How can an easterly wave develop into a hurricane?

An easterly wave can develop into a hurricane primarily through the mechanism described in the correct option, which involves heavy rain and thunderstorms on the eastern side of the wave gaining energy as it moves over warmer water.

Warm ocean waters provide the necessary heat and moisture that fuels storm development. When the easterly wave encounters these warmer waters, it allows for increased evaporation, adding more moisture to the atmosphere. This process leads to the intensification of thunderstorms, which can organize and become more structured under favorable atmospheric conditions. If these thunderstorms develop a well-defined circulation pattern, they can eventually lead to the development of a tropical depression, which may strengthen into a tropical storm and ultimately a hurricane.

In this context, the presence of heavy rain and thunderstorms is significant. These systems tend to have strong updrafts that contribute to the development and maintenance of low-pressure areas, which are essential for hurricane formation. As the system interacts with the warm waters, the latent heat released through condensation in the thunderstorms promotes further development and intensification, creating a feedback loop that helps the system rapidly strengthen.

Other options mention fair weather or the impact of moving over colder water, which do not support hurricane development. Fair weather is less conducive to the energy and moisture needed for a storm