- F1 + F2 = SUM m(0,1,2,3,4,5)
- F1 + F2 = SUM m(0,1,2,6,7)
- F1 + F2 = SUM m(0,1,6,7)
- F1 + F2 = PRD M(0,1,3,4,5)
- F1 + F2 = PRD M(2,3,4,5,6,7)

2 is CORRECT. F2 may be expressed as F2 = SUM m(0,1,6,7) therefore

F1 + F2 = SUM m(0,1,2) + SUM m(0,1,6,7) = m0 + m1 + m2 + m0 + m1 + m6 + m7 = m0 + m1 + m2 + m6 + m7 (recall: x + x = x) = SUM m(0,1,2,6,7)