This is a human-made physical system. A) ecosystem

B) health care system

C) bicycle

D) school system

since it can be assumed that what aslam is making is a template by compiling all the commonly used excel formatting in several worksheets in an excel document, aslam can choose to save it using the .xltx or .xltm format instead. thus, aslam can distribute the templates he has made to his team members in an easier manner.

answer; (a) brake pedal is depressed;

check the image attached

some main parts enter backspace caps lock shift and ctrl