The incident at "three mile island" in 1979 involved a) terrorism. b) nuclear power. c) assassination. d) nuclear weapons.

It is B. It was a release of radioactive material at a power plant in Pennsylvania.

The incident at "Three Mile Island" happened on March 28th, 1979. The plant's mechanical failures resulted in an explosion at the Nuclear Plant. 

The answer is B.

It was an accident, so A and C are not correct. That leaves B and D. D is incorrect because the explosion was at a Nuclear Power PLANT, not at a Nuclear Weapons plant/factory. 

Have a great Day!
-Chris

Ithink the answer is b