Concept:The expression describes following the majority without independent thought.Explanation:The phrase means acting just like everyone else around you.It does not mean physically staying in a crowd (A) or travelling with a crowd (B).It also does not mean simply having many friends (C).The real meaning is that a person allows others to shape their choices and behaviour.Hence, "to do what everyone else is doing" is best described as being unduly influenced by others.Answer:D. be unduly influenced by others