Proboscis gland is a/an

Which of the following acts as a connecting link between echinoderms and chordates?

What is the shape of the alimentary canal in Hemichordata?

Which phylum of animals possesses a $U$-shaped digestive tract?

During a field trip,a student observed a marine organism with a worm-like body. The cylindrical body was divided into a proboscis,collar,and a long trunk. The organism may be . . . . . .

The correct classification of $Balanoglossus$ is: