P : the morning session lasting three hours, was spent
Q : mainly on reviewing
R : in the fourth round of talks
S : the implementation of the decisions taken

The Proper sequence should be:

A. PQRS

B. PQSR

C. PRQS

D. PRSQ

Answer: Option B

Solution(By Examveda Team)

The morning session lasting three hours, was spent mainly on reviewing the implementation of the decisions taken in the fourth round of talks.