respond
v.v. to say or do something as an answer to someone or something else.
v. to say or write something as a reply; to react to a stimulus or situation. Intransitive in its primary sense.
Please respond to my email by Friday.
The emergency services were able to respond to the call within five minutes.
While the building's facade was designed to respond to the local architectural heritage, its interior features cutting-edge sustainable technology.
From Middle English respounden, from Old French respondre, from Late Latin respondō, from Latin respondeō. Cf. Modern French répondre.
The verb is intransitive and requires the preposition 'to' before the object.
He didn't respond my question.He didn't respond to my question.Respond is an intransitive verb and must be followed by the preposition 'to' when an object is present.