Which is not a factor in a fossil organism being useful as an index fossil?

How do you transfer mrna into codons ? i'm so confused : (

The unique structure of the neuron is dedicated to the efficient and rapid transmission of neural signals. the relationship between neurons, the spinal cord, and the brain constitutes an elaborate communication system throughout the human body. all but one of the functions listed below are a result of this interaction.

Plants consume most of their carbon from a. the soil b. the water c. the roots d. the air