Answer:
A. Each organism had a different parent that passed on a set of unique genetic instructions.
Step-by-step explanation:
Organisms can either be single-celled or multicellular. According to this question, a student collects a sample of water from a pond near her home. She then examines a drop of the water under a microscope and noticed it contains four very differently shaped single-celled organisms.
The single-celled organisms are of different shapes because they are from different parents, which passed on a set of unique genetic instructions via their genes to them. Organisms of the same species from the same parent will possess the same shape because they contain same gene which makes them look and behave similar.
However, in this case, the four different shaped single-celled organisms are of DIFFERENT SPECIES and hence, contain individual unique genes that makes them so