To answer this question, the user needs to have knowledge about programming events. In programming, an event is an action or occurrence detected by a program, and it can have a return type.

Now, let's go through each option and explain why it is right or wrong:

A. No return type for events: This option is incorrect because events can have a return type. The return type defines what kind of value the event handler method returns when the event is raised.

B. Double: This option is incorrect because the return type of an event depends on the type of data that the event is passing. An event can have a return type of any valid data type, including Double, Integer, String, and others.

C. Integer: This option is incorrect because the return type of an event depends on the type of data that the event is passing. An event can have a return type of any valid data type, including Double, Integer, String, and others.

D. String: This option is incorrect because the return type of an event depends on the type of data that the event is passing. An event can have a return type of any valid data type, including Double, Integer, String, and others.

The Answer is: A. No return type for events