respond
verb [ I ]
uk/rɪˈspɒnd/ usto say or do something as a reaction to something that has been done or has happened:
respond to sth Aid must double to respond to natural disasters.
respond by doing sth In focussing on carbon reduction, many companies respond by attempting relatively simple fixes.
to say or write something as a reaction to something that has been said or written, for example, a letter:
respond to sth I will need to respond to his email today.