Q16

Adrenocorticotropic hormone (ACTH) is the hormone that stimulates cholesterol conversion to progesterone and testosterone. Progesterone is then converted to cortisol due to the action of an enzyme 21-hydroxylase. If the enzyme is defective, the synthesis of cortisol is reduced, and an excess of testosterone is produced. This results in a disorder called congenital adrenal hyperplasia (CAH).
To diagnose CAH disorder, an ACTH stimulation test is performed. Blood is measured for starting levels of testosterone. ACTH is then injected, and another blood sample is taken and analysed after 120 minutes.
Using the given key which of the following graphs best depicts the changes in the level of testosterone in an ACTH stimulation test?