When this happens gasses dissolved in the magma are able to come out of solution, forming gas bubbles (the cavities) inside it. When the magma finally reaches the surface as lava and cools, the rock solidifies around the gas bubbles and traps them inside, preserving them as holes filled with gas called vesicles.
D is the right answer I took the test. GOOD LUCK
Answer:
An incomplete dominance bad heterozygous individual blends the two traits.
With codominance you'll see both alleles showing their effects but not blending whereas with incomplete dominance you see both alleles effect but they've been blended