Which element is used as a moderator in nuclear reactors?

What is the function of the moderator in a fission reactor?
(a) The moderator absorbs gamma rays. (b) The moderator absorbsslow neutrons.
(c) The moderator decreases the speeds of fast neutrons.
(d) The moderator prevents heat loss from the reactor core.
(e) The moderator prevents the reactor from reaching a criticalstate.

[A] Magnetic confinement of Plasma
[B] Nuclear Fusion
[C] Controlled Nuclear Fission
[D] None of the above

Which of these energy technologies does not rely on a generator to produce electricity?

1. Wind turbine

2. Dynamo 

3. Photovoltaic cell.  

4. Nuclear reactor