Which type of mutation always creates a stop codon?

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.

What are the student's observations and inferences before he starts his investigation?

Has anyone taken the genetics unit test in connexus? not looking for answers, just a little bit what to expect and some with studying.