What does a file extension tell your computer? A. What type of program to open

B. When the file was created

C. Where a program is saved

D. Which file name to display

A. what type of program to open

only #2 represents an object at rest on a table.

in #1, there is no normal force due to the table; the object is accelerating downward.

in #3, the vertical forces are not balanced; the object is accelerating downward.

in #4, neither the vertical nor the horizontal forces are balanced. the object is accelerating upwards and to the right.