Only one fruit develops from a single flower. This type of fruit is known as ___________ .

The correct option is A simple fruit
$\bullet$ When only one fruit is formed from a single flower with a single ovary, such fruits are called simple fruits. Examples are mango and tomato.
$\bullet$ When one fruit is formed from a flower that has multiple ovaries, such a fruit is called an aggregate fruit. Examples are custard apple and blackberry.
$\bullet$ When the fruits are formed from an inflorescence, such fruits are called multiple fruits. In an inflorescence, there are many flowers and each of them contains an ovary. Examples are jackfruit and pineapple.
$\bullet$ Sometimes fruits are formed from parts other than the ovary, such as pedicel or the thalamus. These fruits are called false fruits. Cashew apple is an example.