Answer:
many alveoli are present in the lungs with a shape that further increases surface area. Thin walls - alveolar walls are one cell thick providing gases with a short diffusion distance. Moist walls - gases dissolve in the moisture helping them to pass across the gas exchange surface.
Explanation:
If we draw up a Punnett square, we will see that after crossing two heterozygous individuals the possible offspring are RR, Rr, Rr and rr:
R r
R RR Rr
r Rr rr
Now to produce red flowers, an individual must be either homozygous dominant (RR) or heterozygous (Rr) and so from the Punnett square we can see that 3/4 of the offspring would produce red flowers. If we apply this ratio to 100 offspring, then we get:
3/4*100 = 75 offspring with red flowers, thus the answer is C
