Which one of the following structures in Pheretima is correctly matched with its function?

Solution- In a mature earthworm, segments $14^{\text{th }}-16^{\text{th }}$ are covered by a prominent dark band of glandular tissues called clitellum which secretes cocoon where fertilization and development takes place. In alimentary canal, muscular gizzard ( $8^{\text{th }}-9^{\text{th }}$ segments) helps in grinding the soil particles and decaying leaves, etc. The characteristic feature of the intestine between $26^{\text{th }}-35^{\text{th }}$ segments is the presence of internal median fold of dorsal wall called typhlosole. This increases the effective area of absorption in the intestine. In each body segment, except the first, last and clitellum, there are rows of S-shaped setae, embedded in the epidermal pits in the middle of each segment. Setae can be extended or retracted. Their principal role is in locomotion.