Point Out the Correct Statement

Multiple Choice

Point out the correct statement.

A) mems is a class of very small sensor or actuator devices where small mechanical systems are driven by electricity to indicate a position
B) the incorporation of low-cost geo-sensors in the form of gps chips into mobile devices opens the mobile user to a whole range of services based on the client's location
C) the iphone uses the proximity sensor to turn the screen off when a user puts the phone to his face
D) all of the mentioned