RIR chickens- Rooster or hen?

[Bairchickens]

Hello- my family is new to BYC and to chicken owning. We have 3 Rhode Island Reds that are 2-3 months old. One is significantly bigger than the others, has more of a comb and darker feathers.

We want to know if it is a hen or a rooster. Please respond asap.

 

[eHenderson]

Roo

 

[Aacre]

Rooster.