Help me with my anatomy homework

The table shows dates and appearance of index fossils. which rock layers can be dated most precisely? a) a layer containing both a fossil 4 and a fossil 3 b) a layer containing both a fossil 2 and a fossil 3 c) a layer containing both a fossil 1 and a fossil 4 d) a layer containing both a fossil 1 and a fossil 2

Glycogen is an energy-storage molecule in humans. a hormone that is called insulin controls the storage of glycogen in the liver. insulin is made up of amino acids.

Which of the follow describes a disadvantage secondary sources have compared to primary sources?