If P, Q, R are subsets of the universal set U, then $$(P\cap Q\cap R) \cup (P^c \cap Q \cap R) \cup Q^c \cup R^c$$ is
Can we treat these like Boolean expression and solve?
Like PQR + P'QR + Q' + R'. and minimise this.
Is this method always correct?
so option d
It is quite unfortunate. Never before ...