Directions : $(28-29)$ In each of the following letter series, some of the letters are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
$\text{pqr__rs_rs__s_q_}$
- $\text{spqpprr}$
- $\text{pqrrppq}$
- $\text{sqppqpr}$
- $\text{sqprrqr}$