C: The daughters received a random set of genes from both of their parents.
The physical appearance of an individual is determined by their genes, which are inherited from their parents. Each parent contributes half of their genes to their offspring, and the combination of genes from both parents determines the physical characteristics of the offspring.
When the two daughters inherit genes from both their parents, they receive a random set of genes from each parent, which can result in both similar and different physical features. Therefore, statement C is the best explanation for why the daughters' physical appearance includes both similar and different features.