Which particle has a postive charge? neutron, electron, proton or beta particle

The answer for #3 is c but i don't know why

Alidded glass container is filled with a colored gas. after a period of time, it is observed that the gas is uniformly spread throughout the box and that the movement has slowed considerably. next, a warm iron plate is carefully placed under the box. why is there resumed movement of the gas in the container?

What if it is did darwin used to support his theory of evolution