a group of students is observing these two species of squirrel in forming conclusions about how they are alike and different which type of investigation is the group doing

Although there are no options but this investigation is a COMPARATIVE investigation

Explanation:

Scientific investigations aims at satisfying a curiosity or a way of explaining natural phenomena. There are three types of investigations viz: descriptive, comparative and experimental investigations.

Comparative investigation is a type of investigation that involves collecting data on different organisms, locations etc for the sole purpose of comparing. It aims at confirming if there is a relationship between i.e. similarities/differences. In this question, two species of squirrels are being observed for their similarities and differences i.e. the aim of the investigation is COMPARISON. Hence, it is an example of comparative investigation

i would say it is

you can have just about every answer you can think of