What are the student's observations and inferences before he starts his investigation?

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.

the answer to your question is b

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.