I think it’s C but not precisely sure about it
Several species of warblers can live in the same spruce tree only because they occupy different nitches within the tree. So option "c" is the correct option as far as the given question is concerned. These birds may not be of the same species but they do have some similarities like they are very vocal and can be rarely seen but definitely heard. All species of warblers are insectivorous and also very small. As they are small so identifying them can be very difficult for a person. These birds are mostly dull greenish or brownish in color.
This is only explanation. What are the questions for it?
Answer:
Together,the number of protons and the number of neutrons determine an elements isotopes have slightly different mass numbers, the atomic mass is calculated by obtaining the mean of the mass numbers for its isotopes.
hope it is helpful....