During formation of vertebrae, the most anterior embryonic segment that expresses Hoxc6 marks the end of the cervical (neck) vertebrae and the beginning of the thoracic (rib) vertebrae. All mammals have seven cervical vertebrae.
The chick and the goose have the same number of thoracic vertebrae. T/F

The correct answer is - false.

Explanation:

The thoracic vertebrae are normally known as the ribs. Thoracic vertebrae are the bones that form the spine. The major role of the ribs is to protect the vital organs such as lungs, heart and support the rib cage.

The number of thoracic vertebrae of goose and chick is different. The number of ribs in the chick are seven. Among the 7 the first two thoracic vertebrae did not reach the sternum however the rest attached to the sternum the point of attachment. In goose, the thoracic vertebrae are 9 in number. In birds, there is complicated the fusion of the thoracic including the 7th vertebrae of ribs.

Thus, the correct answer is - false.

the answer to your question is:

c. complementary base-pairing

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).