Which equation is an identity? 3(x – 1) = x + 2(x + 1) + 1 x – 4(x + 1) = –3(x + 1) + 1 2x + 3 = 2 x plus 3 equals StartFraction one-half EndFraction left-parenthesis 4 x plus 2 right-parenthesis plus 2.(4x + 2) + 2 StartFraction one-third EndFraction left-parenthesis 6 x minus 3 right-parenthesis equals 3 left-parenthesis x plus 1 right-parenthesis minus x minus 2.(6x – 3) = 3(x + 1) – x – 2Which groups of animals participate in adaptive social behavior?