Buffer overflows happen because:

A.
Buffers can only contain a certain amount of data.

B.
The length of the data is not checked at time of input.

C.
Buffers are weak and easy to exploit.

D.
The system�s memory is insufficient.

Explanation:
Buffer overflows happen if inputted data is not checked. This can
corrupt memory when more data is entered, causing extra instructions to be executed
by the CPU.