Question

1. cephalochordates have a backbone that extends from their tail to where?

their heart
their anus
their gills
their head

Explanation:

Cephalochordates (like lancelets) have a notochord (a structure related to the backbone) that extends from the tail to the head. This is a key anatomical feature of cephalochordates, distinguishing their chordate structure. The other options (heart, anus, gills) do not align with the known anatomy of cephalochordates' notochord/backbone - like structure.

Answer:

D. their head