By far, the largest security exposure in application system development relates to

A.
Maintenance and debugging hooks.

B.
Deliberate compromise.

C.
Change control.

D.
Errors and lack of training

Explanation:
Maintenance hook – instructions within a program’s code that enable the developer
or maintainer to enter the program without having to go through the usual access control and
authentication processes. They should be removed from the code before being released for
production; otherwise, they can cause serious security risks. They are also referred to as
trapdoors. – Shon Harris All-in-one CISSP Certification Guide pg 933