A student observes an animal that has a backbone, gills, and scales. It lays eggs and is cold−blooded.
What does this animal have in common with all mammals?
Answer Options with 5 options
A. a backbone
B. gills
C. scales
D. egg−laying
E. cold−blooded
If you think about it, us mammals (humans are mammals) don't have gills, scales, we do not lay eggs, and we are not cold-blooded. But we do have a spine, or backbone.