An interface to a library of software functions that provide security and cryptography services is
called:

A.
A security application programming interface (SAPI)

B.
A confidentiality, integrity and availability application programming interface (CIAAPI)

C.
An assurance application programming interface (AAPI)

D.
A cryptographic application programming interface (CAPI)

Explanation:
CAPI is designed for software developers to call functions from the library and, thus, make it easier
to implement security services. An example of a CAPI is the Generic Security Service API (GSSAPI.)
The GSS-API provides data confidentiality, authentication, and data integrity services and supports
the use of both public and secret key mechanisms. The GSS-API is described in the Internet Proposed
Standard RFC 2078. The other answers are made-up distracters.