Final answer:
Milk is produced in the glandular tissue of the breast within the lobules' alveoli, which are then squeezed through lactiferous ducts to the nipple. The breasts contain other tissues and structures, but these are not responsible for milk production. The correct option is D. Glandular tissue.
Step-by-step explanation:
Milk is produced during lactation in the glandular tissue of the breasts. Each breast contains multiple lobules, which are part of the mammary glands. Within these lobules are clusters of milk-secreting cells known as alveoli. The process of lactation involves the secretion of milk from these cells, filling the alveoli, and then being squeezed into lactiferous ducts that lead to the nipple. Surrounding the alveoli are myoepithelial cells that, when stimulated, contract to push the milk towards the lactiferous sinuses. From there, an infant can extract the milk by suckling at the nipple.
The areola and nipples play roles in the lactation process, but they are not where milk production occurs. The areola contains Montgomery glands which secrete an oily fluid to protect the nipple during breastfeeding, while the nipples provide the exit point for milk through the lactiferous ducts in response to a baby's suckling. Breast size is largely determined by the amount of fatty/fibrous tissue present and does not affect the quantity of milk produced.