Final answer:
Possibility 1 (Bb) includes one copy of the dominant gene and represents an offspring with a full head of hair.
Step-by-step explanation:
The Punnett square shows the possible genotypes and phenotypes of the offspring. In this case, the Punnett square represents two people with recessive genes for baldness, which would be bb. To produce an offspring with a full head of hair, we would need at least one copy of the dominant gene, B. Looking at the Punnett square, Possibility 1 (Bb) includes one copy of the dominant gene, so it represents an offspring with a full head of hair.