Answer:
(A)-electron
Step-by-step explanation:
Particles can be classified into:
- Leptons: particles which do not feel the strong interaction
- Hadrons: particles which interact by strong nuclear forces (they are actually not fundamental particles, since they are composed of quarks)
- Boson: the mediators of the four fundamental forces
The given options in this problem are:
(A)-electron --> LEPTON (because it does not feel the strong interaction)
(B)-proton --> HADRON (it consists of quarks)
(C)-neutron --> HADRON (it consists of quarks)
(D)-photon --> BOSON (it is the mediator of the electromagnetic force)
(E)-boson --> BOSON
So, the only lepton among the choices is (A) electron.