What is a buffer overflow attack and how does it occur?

a) A buffer overflow attack occurs when the developer fails to include code that checks whether an input string fits into its buffer array.
b) A buffer overflow attack happens when the developer fails to include code that checks whether an input string fits into its buffer array.
c) A buffer overflow attack occurs when the developer fails to include code that checks whether an input string fits into its buffer array.
d) A buffer overflow attack happens when the developer fails to include code that checks whether an input string fits into its buffer array.