Explain why methane has a low boiling point?

Oh, it's you again. Alright, Methane is a hydrocarbon and its formula is CH4.

Within HydroCarbons, you've got something called London-Dispersion Forces. And it's a very weak type of intermolecular force. This weak IMF is the reason that CH4 and many other organic/hydrocarbons are either gaseous or liquid. 
The reason it has a low boiling point is because it doesn't require much energy/heat in order to break the weak bonds within the molecule and covert it into a gas. 

Methane is a hydro carbon. It means it contains only hydrogen and carbon. Its formula is CH4. The simplest ans to why methane has a low boiling point is the presence of only one carbon. the higher the amount of carbon, the higher the boiling point. Hope this helps you. 

Ais the correct answer

The correct answer is c. orbital shape. "the angular momentum quantum number l describes the shape of an orbital. it corresponds to each orbital type, i.e. (0,1,2,−1)=(s,p,d,f,g,"