Concept:Equatorial rainfall is mainly caused by intense heating and convectional lifting of moist air.
Explanation:In the equatorial region, the sun heats the earth’s surface strongly, causing warm, moist air to rise rapidly.
As the air rises, it cools, condenses, and forms heavy thunderstorms and rainfall.
This type of rainfall is called convectional rainfall.
Options such as orographic, harmattan, and cyclonic effects are not the main causes of equatorial rainfall.
Answer:A. conventional effect (convectional rainfall)