Julie was diagnosed with an aggressive tumor of the thyroid. surgery was performed to remove the thyroid. however, post-operatively, julie's blood calcium levels began declining to life-threatening levels. this decline is most likely due to . thyroid hormone replacement therapy after the surgery. b. damage to the anterior pituitary during surgery. c. accidental removal of the parathyroid glands during surgery. d. improper laboratory handling of blood samples. e. post-traumatic stress disorder.

c. accidental removal of the parathyroid glands during surgery

Explanation:

Parathyroid gland is found closely situated at the back of the thyroid gland in the human neck region. Regulation of serum calcium levels in the body is a major function of the parathyroid gland through the secretion of a hormone called parathyroid hormone or parathormone.

During the surgery conducted to remove the thyroid gland, it is very likely that the parathyroid glands were accidentally damaged or removed. This most likely led to the non--secretion of parathormone, which is responsible for secretion of calcium in the body, when calcium levels drop.

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).