Answer: Layer a is 500 million years old.
Explanation:
Trilobite is a member of the group of extinct arthropods found as fossils and they can be identified by the three-lobed as well as three segmented forms. These were the marine animals. These were appeared initially in the Cambrian Period. They used to live 542 million years ago so the fossils can be estimated to be aged of 500 above years old. These animals used to dominate in the sea area.
Venus is often called the sister planet of Earth because of its size, mass, and what its material its made of.
1. what it looks like 2. smells 3.feel 4.what happens if mixed with other properties
I would think it would be C