Three resistances P, Q, R each of $2 \Omega$ and an unknown resistance S form the four arms of a Wheatstone bridge circuit. When a resistance of $6 \Omega$ is connected in parallel to S the bridge gets balanced. What is the value of S ?

Question

( A ) $6 \Omega$
( B ) $2 \Omega$
( C ) $3 \Omega$
( D ) $1 \Omega$