Emily's body starts to develop secretory glands at the end of the milk ducts in the breasts. Based on the given information, we can say that Emily is most likely to be in the stage.

Thelarche

Explanation:

In females, thelarche represents the start of puberty and as such it marks the beginning of the secondary development of the mammary glands known as breasts. This pubertal development usually occur in females that are between the ages of 8 years and 12 years due to the secretion of hormones such as estrogen.

In this scenario, Emily's body starts to develop secretory glands at the end of the milk ducts in the breasts. Based on the given information, we can say that Emily is most likely to be in the thelarche stage because she is beginning to experience breast budding.

that is wrong, its not thymus.