what are some density - dependent limiting factors and density - independent limiting factors that may influence the sea otter population as it tries to recover

You are working in the lab and are working with the same element but with varying isotopes of the element. you are working with c-11, c-13, c-14, and c-15. what is the average atomic mass of this element? (use periodic table) a- 12 b-15 c-14 d-13