Refer to figure.
With all these read back questions, a good approach for both the flight deck and the exam room is to:

• Read back the required information in exactly the same order that it was given
• Put your call sign at the end

Looking at the answer options:

Cleared for take-off, Fastair 54 --> INCORRECT. Missing the runway designator.

Runway 26, cleared for take-off, Fastair 54 --> CORRECT. You must always read back the runway designator.

Wilco, Fastair 54 --> INCORRECT. Incorrect read back for the clearance to take-off and also missing the runway designator.

Runway 26, cleared for take-off --> INCORRECT. Missing the aircraft's callsign.