Answer:
Option C
Explanation:
Let p,q, r, s , m and n be the position vectors of P.Q,R,S,M and N be respectively.
Given ,M and N are the mid-points of PQ and RS respectively of quadrilateral PQRS
m=p+q2 and n=p+s2 .......(i)
Now, PS QR = (PV of S- PV of P)+(PV of R-PV of Q)
= s+p+r-q
=(r+s)-(p+q)
=2n-2m [from Eq.(i)]
=2(n-m)=2MN