Question

In figure 16-2 is the temperature of the material within the cylinder greatest during the intake stroke, compression stroke, power stroke, or exhaust stroke?

Answer 1

Technically, we have no way of knowing that without seeing Figure 16-2.
So the question should be reported for incomplete content.  But I'm
going to take a wild stab at it anyway.

There's so much discussion of 'cylinder' and 'strokes' in the question,
I have a hunch that it's talking about the guts of a 4-stroke internal
combustion gasoline engine. 

If I'm right, then the temperature of the material within the cylinder is
greatest right after the spark ignites it.  At that instant, the material burns, 
explodes, expands violently, and drives the piston down with its stiff shot
of pressure.

This is obviously happening because of the great, sudden increase in
temperature when the material ignites and explodes.

It hits the piston with pressure, which leads directly to the power stroke.