The basic bilaterian body form plan can be thought of as simply .a. a series of boxesb. several joined ringsc. many concentric circlesd. a tube within a tube

A tube within a tube

Explanation:

Most animals have a body plan best described as a tube within a tube. This plan calls for two openings: one for food to enter the body (mouth), one for wastes to leave the body (anus). The tube-within-a-tube plan allows specialization of parts along the tube, such as a stomach, intestine, etc. another body plan is the sax like body plan, which had only one opening. They are 10% less effective

its raceist

explanation:

it dosn't have red,yellow,green,blue,indigo,violet,or purple

im not intirely sure but i think the anwser is d relative humidity