Option C
Given, $((p,q),(r,s)) \in R$ iff $p-s=q-r$
Simple check:
Let $(p,q) = a \ \& \ (r,s) =b \implies aRb$
For Reflexive:
$a R a? \implies (p,q) R (p,q)?$
$p-q \neq q-p, hence\ not \ reflexive.$
For Symmetric:
If $aRb$ then $bRa \ ?$
$(p,q)R(r,s) → (r,s)R(p,q) ? $
LHS : Is given $((p,q),(r,s)) \in R$ iff $p-s=q-r$
RHS: $r-q = s-p \implies p-s = q-r$
$LHS = RHS , hence \ symmetric$