What is a cursor?
a.
subject of your communication
b.
form of a template
c.
blinking vertical line on your screen
d.
conclusion of your communication

A cursor is a blinking vertical line on your screen

Explanation:

Cursor here points to a mouse cursor. A mouse cursor is a movable object on the screen which can provide the next action to the computer. In other words, this would possibly provide input to the user to perform the desired action.

A cursor is also called as arrow and it can be replaced to any image accepted by the cursor. It turns as a blinking vertical line on your screen especially when you are writing or editing a document.

Here were, the text would be typed or text would be selected.