Figure gives a system of logic gates. From the study of truth table it can be found that no produce a high output `(1)` at `R`, we must have

Options

A. `X=0, Y=1`
B. `X=1,Y=1`
C. `X=1,Y=0`
D. `X=0,Y=0`

Answer

C

Explanation

The truth table can be written as
`|(X,Y,bar(X),bar(Y),P=bar(X)+Y,Q=bar(XbarY),R=bar(P+Q)),(0,1,1,0,1,1,0),(1,1,0,0,1,1,0),(1,0,0,1,0,0,1),(0,0,1,1,1,1,0)|`
Hence `X=1,Y=0` gives output `R=1`