In the quest to understand the basis of infertility in humans, researchers have identified a mutation in a gene associated with chiasmata. this protein normally acts to promote homologous recombination. why might a defect in homologous recombination have consequences for fertility?

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

c is the answer. hope this