Consider a standard additive model consisting of rules of the form of
If $x$ is $A_i$ AND $y$ is $B_i$ THEN $z$ is $C_i$. Given crisp inputs $x=x_0, \: y=y_0$ the output of the model is
option c
STANDARD ADDITIVE MODEL (SAM) includes the centroid defuzzification technique. here
IF x is AND y is THEN z is Given crisp inputs x= x0, y = y0,
z=centroid(ΣiμAi(x0)μBi(y0)μCi(z))
source : http://shodhganga.inflibnet.ac.in/bitstream/10603/134769/9/09_chapter%203.pdf