What are index fossils and how can they be used to help find the relative age of the rock layers?

The answer is a if u read the definition it makes sense

The main role of dna in the  cell is the long-term storage of information. it is often compared to a blueprint, since it contains the instructions to construct other components of the  cell, such as  proteins  and rna molecules.the main function of rna is to carry information of amino acid sequence from the genes to where  proteins  are assembled on  ribosomes  in the  cytoplasm. mark brainliest, my work is good.