Respond

Respond= a verbal reply; answer: ‘She didn't respond to my question.’

Respond is a verb: ‘We are still waiting for them to respond.’

Response is a noun: ‘I’m surprised we got such a quick response.’ ‘In response to your last comment, I’m afraid that I don’t agree.’

Responsible is an adjective. Responsible for (doing) sth: ‘Who’s responsible for roof repairs – you or the landlord?’ ‘The person responsible for leaking the story to the press has been forced to resign.’