Consider the following logic circuit whose inputs are functions $f_1, f_2, f_3$ and output is $f$
$f_1(x,y,z) = \Sigma (0,1,3,5)$
$f_2(x,y,z) = \Sigma (6,7),$ and
$f(x,y,z) = \Sigma (1,4,5).$
Here f2 should be : f2(x,y,z)=Σ(6,5) as given in original paper.
Here we have NAND - NAND Circuit, we can convert it to following AND - OR circuit. (As NAND is bubbled OR). Now it is easy to solve this question. F1 AND F2 = 0. SO whatever f3 is directly passed to output. So answer is A.