What type of study is performed under tightly controlled situations and often involves animals?

answer; ///i believe the correct answer is (aids) acquired immune deficiency syndrome;

it's     c       this is a cell (b) with a nucleus (c) containing dna (a). the dna is organized into chromosomes (d). a section of the chromosome that codes for a trait is called a gene (e).

mammal

explanation:

b brown mice / white sand dunes