Which one exhibits concentric tube-within-tube plan ?

Which one of the following exhibits concentric 'tube within tube' plan ?

Which one of the following exhibits concentric tube within tube plan ?

Which one of the following exhibits concetric "tube within tube" plan

Sponges have tube-within-a-tube body plan.

Which of the following animals has tube- within-tube type of body plan evolved along deuterostomic evolutionary line ?

Animlas which are triploblatic with tube- within - tube type of body plan and embryonic blastopore forms anus (deutterostomia ) are

Which of the following animals has tube- within-tube type of body plan evolved along deuterostomic evolutionary line ?

Animlas which are triploblatic with tube- within - tube type of body plan and embryonic blastopore forms anus (deutterostomia ) are

Mention the animals that exhibited a 'tube-within-a-tube' organisation for the first time? Name their body cavity.