Answer: Mostly due to alleles.
Explanation: ...
The answer is d. Hope it help
Answer:
A. There are fossils of extinct ancestors of horseshoe crabs and the species is still alive today.
Explanation:
C and D have more to do with how it can be a fossil. It is a living fossil because its ancestors have been found in fossils, yet it continues to live today.
There are four basic types of animal tissue, these are connective, epithelial, nervous, and muscle tissues.