Final answer:
Testosterone does not stimulate breast development; this is a role mainly played by estrogen hormones. Testosterone is instead responsible for secondary male sex characteristics such as muscle bulk and facial hair growth.
Step-by-step explanation:
Stimulation of breast development is not an effect that can be attributed to testosterone. Testosterone is primarily involved in promoting and maintaining secondary male sex characteristics.
Secondary sex characteristics in males include increased muscle mass, deepening of the voice, and growth of facial, axillary, and pubic hair. Conversely, estrogen hormones, particularly estradiol, are chiefly responsible for the development of secondary sexual characteristics in females, such as breast development and fat deposition in areas like the hips, buttocks, and thighs.
However, while testosterone can lead to some increase in muscle bulk and might play a role in the physical changes during male puberty, it does not stimulate breast development; this is predominantly an estrogen-mediated process.