SAT English Practice Question

A team of scientists studying animal communication recently discovered a new form of communication used by a species of fish. The scientists believe this form of communication might be particularly useful for the species because it can be used to communicate in the dark. To determine whether this is true, the team conducted experiments in the lab. Which choice completes the text so that it conforms to the conventions of Standard English?

1. A.in the lab;
2. B.in the lab,
3. C.in the lab:
4. D.in the lab.