Sal drew a diagram to compare vertebrates and invertebrates.
((picture at the bottom))
choices:

are eukaryotic
have an outer skeleton
are heterotrophs
have a backbone

D, Have A Backbone

Explanation:

Animals that have a backbone are called vertebrates. The backbone is is a column of bones that supports the body, and also protects the spinal cord. The back is made up of many separate bones, called vertebrae. The backbone is part of a vertebrate's supportive internal skeleton.

14 days is the half-life of phosphorus-32

sorry i was late, but i don't know what assignment your talking about, i'm in flvs as well, im in earth space science. but u are behind pace bc every class should be in the 3's or 4'