Which bomb works on the principle of Nuclear fusion?
A. Atom bomb
B. Hydrogen bomb
C. Neutron Bomb
D. Nuclear reactor

Hint Nuclear fusion is basically a type of chemical reaction in which two or more than two atomic nuclei react with each other and combine to form one or more different atomic nuclei or subatomic particles. It can be both exothermic and endothermic depending upon nuclear mass of the reactants.

Complete step by step answer
Let us first discuss Nuclear Fusion.
Nuclear fusion is basically a type of chemical reaction in which two or more than two atomic nuclei react with each other and combine to form one or more different atomic nuclei or subatomic particles. This reaction can be both exothermic and endothermic depending upon nuclear mass of the reactants. This energy can be used to produce a bomb.
Hydrogen bombs work on the principle of Nuclear fusion. It uses the reaction between the isotopes of hydrogen i.e. deuterium and tritium for the explosion. This is a highly exothermic reaction. This type of bombs is also referred to as “Thermonuclear weapons”.
On the other hand, Atom bombs work on the principle of nuclear fission in which a radioactive element such as uranium or plutonium splits spontaneously into two or more lighter nuclei. This is an exothermic reaction and releases a tremendous amount of energy.

Hence, option B is correct.

Note Initially the nuclear fission reaction is used to trigger the fusion process and the fusion process themselves triggers more fission. Till date, only six countries have conducted thermonuclear weapon tests: the US, UK, Russia, India, France and China.
If the nuclei reacting in the fusion reaction are lighter than Fe-56 or Ni-62 then the reaction will release energy. So, if the nuclei reacting in the fusion reaction are lighter than these, the reaction will be exothermic whereas if they are heavier than these, the reaction will be endothermic.