In a flowchart, the diamond form is used to represent?

--------- C. a decision point. -------

The diamond form is used to make a decision point  in the flow chart . 

In flowchart the diamond form is represents the Decision Point. 

If in the decision point if there is Yes flag the process will proceed to the next step otherwise go back to the appropriate previous step.

A diamond form in flowchart is use as a decision point, wherein you are given two possible outcome, the Yes or No, of the situation/problem.

an operation, all of the above mentioned should be included in diamond form presentation