Correct Answer: qprpq

Solution : Given:
r_p_q_rq_p_r

To fill in the blanks, divide the series into clusters of 3 letters – r_p / _q_ / rq_ / p_r
Let's check each option –
First option: qrprp; r q p / r q p / rq r / p p r (No repeated pattern found.)
Second option: pqrqp; r p p / q q r / rq q / p p r (No repeated pattern found.)
Third option: qprpq; r q p / p q r / rq p / p q r (rqp and pqr are repeated alternately.)
Fourth option: qprpp; r q p / p q r / rq p / p p r (No repeated pattern found.)

So, the series becomes→rqppqrrqppqr. Hence, the third option is correct.