Answer:
The data the student must collect is the number of protists in each sample.
Step-by-step explanation:
The student wants to know if the number of protists is influenced by the depth of the aquatic environments. For this reason, the student went to a lake and collected water samples at different depths. What the student should do now is to place these samples in a telescope, count and note how many protists he has in each sample. After he does this with all samples, he should look at his notes and compare the amount of protists equivalent at each depth. In this way the student will know if the amount of protists is influenced by the depth of the water in an aquatic environment.