Given the findings in the passage, which additional result most strongly indicates that the tgfbr1 and tgfbr2 receptors regulate tgfβ-dependent epithelial proliferation?

Option B.

Explanation:

The first experiment of the passage shows that treatment with TGFBR1 and TGFBR2 antagonists led to lower levels of epithelial cell production. For this conclusion to be strongly valid, we want to show a positive correlation between TGFBR activity and epithelial proliferation.

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.