What the equivalent resistance between any two opposite corner points of a quadrilateral, if the sides of the quadrilateral are of equal resistance R ? 

(a) 

(b) 

(c) 

(d) 

What the equivalent resistance between any two opposite corner points of a quadrilateral, if the sides of the quadrilateral are of equal resistance R ? 

(a) 

(b) 

(c) 

(d) 
