Solution:(c) My friends say, "Many young people are very active on social media now." (correct)(a) My friends say, "Many young people were very active on social media now." (incorrect tense)
(b). My friends said, "Many young people were very active on social media then." (incorrect reported verb, tense, and then)
(d). My friends are saying, "Many young people are very active on
social media then." (incorrect reported verb and then)