The correct answer is (B):log12 81 = p ⇒ log1234 = p4log12 3=p⇒ p/4 = log12 33(4-p/4+p)=3(1-p/4/1+p/4)= 3(1-log12 3/log12+log12 3)= 3(log(12/3)/log(12/3))= 3log4/log36 = 3log36 4= log68