<prompt> Child knows hisher sex by age of-2 year3 year4 year5 year  <response>: Ans, is b i.e., 3 year AgeMilestone2 MonthSocial smile3 MonthRecognise mother6 MonthStmger anxiety9 Monthwave bye - bye12 MonthComes when called15 MonthJargon18 MonthsCopies parents task2 yearAsk for food, drink, shows toys3 yearKnow full name gender4 yearPlays in group.5 yearHelps in household task, decrease undresses 