DiGeorge syndrome is characterized by which of the following?

DiGeorge syndrome is primarily characterized by hypoplasia or aplasia of the thymus and parathyroid glands. This condition arises due to a deletion of chromosome 22q11, leading to developmental issues that result in decreased T-cell production and hypoparathyroidism.

The option indicating thymic-parathyroid dysplasia is the correct one because it accurately reflects the underdevelopment of these structures. The lack of development leads to immunodeficiency due to compromised T-cell function and calcium disturbances due to insufficient parathyroid hormone which regulates calcium levels in the body.

The other options suggest conditions that do not fit the clinical picture of DiGeorge syndrome. For example, hyperplasia of the thymus or parathyroid glands would not be consistent with the syndrome's characteristics. Severe hypercalcemia is also not typical, as patients often experience hypocalcemia due to low parathyroid hormone levels. An excessive immune response is contrary to what is seen in this syndrome; instead, patients exhibit an increased susceptibility to infections due to immunocompromise from thymic hypoplasia.