Which hormone is involved in increasing blood glucose levels?

Cortisol is the correct choice because it is a hormone produced by the adrenal glands in response to stress and low blood glucose levels. One of its key functions is to increase blood glucose through gluconeogenesis, a metabolic pathway that generates glucose from non-carbohydrate sources, such as amino acids and glycerol. Cortisol also decreases glucose uptake in tissues, particularly in muscle and fat, which helps to maintain higher levels of glucose in the bloodstream during times of stress or fasting.

In contrast, insulin is primarily responsible for decreasing blood glucose levels by facilitating the uptake of glucose into cells, while prolactin's main role revolves around lactation and has little to do with glucose regulation. Thyroid stimulating hormone primarily regulates thyroid activity and metabolism rather than directly affecting glucose levels.