Yes, RESPONSE is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, S 1, P 3, O 1, N 1, S 1, E 1.

Is it a valid word?

RESPONSE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a result
a bodily process occurring due to the effect of some antecedent stimulus or agent
a statement (either spoken or written) that is made to reply to a question or request or criticism or accusation
the manner in which something is greeted
a phrase recited or sung by the congregation following a versicle by the priest or minister
the speech act of continuing a conversational exchange
the manner in which an electrical or mechanical device responds to an input signal or a range of input signals