The basic Electronic Access Control (EAC) components required for access doors are an
electromagnetic lock,

A.
A credential reader, and a door closed sensor.

B.
A card reader, and a door open sensor.

C.
A biometric reader, and a door open sensor.

D.
A card reader, and door motion detector.

Explanation:
We have not been able to find any reference to this question really. So we are
going with “A credential reader, and a door closed sensor”.
“In addition to smart and dumb cards, proximity readers can be used to control physical access. A
proximity reader can be passive device, a field-powered device, or a transponder.” – Ed Tittle
CISSP Study Guide (sybex) pg 650