Final answer:
The outermost covering of a fruit is called the exocarp and it is responsible for protecting the fruit. In the case of a lemon, the yellow, bumpy skin that you see is the exocarp.
Step-by-step explanation:
The outermost covering of a fruit is called the exocarp.
Fruits generally have three parts: the exocarp (the outermost skin or covering), the mesocarp (middle part of the fruit), and the endocarp (the inner part of the fruit). Together, all three are known as the pericarp. In the case of a lemon, the yellow, bumpy skin that you see is the exocarp.