Select the combination of letters that when sequentially placed in the blanks of the given series will complete the series.
_ msk _ prm _ kt _ r _ s _ tpr _ skt _

A

r,s,t,p,m,k,m,p

B

r,t,s,p,m,m,m,p

C

r,t,s,p,m,k,k,p

D

r,t,s,p,m,k,m,p