20 did not appear for any of the three methods. Hence, the total number of students who appeared in the tests (400−20)=380. (240+160+200)=600 students = exactly I+2( exactly II) +3( exactly III) ⇒2( exactly II) +3( exactly III )=400 Exactly I +exactly II + exactly III = 380⇒ exactly II+ exactly III=180⇒2(exactly II) +2( exactly III) = 360⇒ exactly III =40 Therefore, exactly II=180−40=140. Hence, the correct option is A.