The relation between the number of pairs forming a kinematic chain and the Number of links is A l = 2p-2 B l = 2p-3 C l = 2P-4 D l = 2p-5

I believe answer is choice "C", I =2P-4

Please see page "16" of this article:

http://site.iugaza.edu.ps/mhaiba/files/2013/09/CH-5-Simple-Mechanisms.pdf

This is a nice article which discuss this subject in more details.

 "C", I =2P-4 for lower pairs.

I chose "C"

Good answer Mr. Tartir.

If each link is assumed to form two pairs with two adjacent links, then the relation between number of pairs (p) forming a kinematic chain and number of links (l) may be expressed as:

l =2p –4

2p-3