It is very easy
P : a great deal more than one realises
Q : may mean
R : that a phrase that one does not quite understand
S : to persuade oneself

The Proper sequence should be:

A. RSQP

B. SPQR

C. SRQP

D. RQPS

Answer: Option B

Solution(By Examveda Team)

It is very easy to persuade oneself a great deal more than one realizes may mean that a phrase that one does not quite understand.