Q. Ctrl, Shift and Alt are called .......... keys.

Explanation by: Mr. Dubey

Ctrl, Shift, and Alt are known as modifier keys because they do not perform a function on their own but modify the function of other keys when used in combination.
Other Options:
(B) Function → Incorrect, as function keys are F1 to F12 on the keyboard.
(C) Alphanumeric → Incorrect, as alphanumeric keys include letters (A-Z) and numbers (0-9).
(D) Adjustment → Incorrect, as there is no category of "adjustment" keys in computing.
Thus, the correct answer is (A) Modifier.