**Core Concept**
Galactokinesis refers to the physiological process of milk ejection in the breast, involving the contraction of myoepithelial cells in response to signals from the hypothalamus and pituitary gland, particularly through the release of oxytocin.

**Why the Correct Answer is Right**
Galactokinesis specifically denotes the **ejection of milk** from the breast, not its production or maintenance. This process is mediated by oxytocin, which acts on myoepithelial cells surrounding the lactiferous ducts, causing contraction and facilitating milk expulsion. It is distinct from galactogenesis (milk synthesis) or lactation maintenance.

**Why Each Wrong Option is Incorrect**
Option A: Sustaining lactation refers to the ongoing maintenance of milk production, not the ejection phase.
Option B: Secretion of milk is a broader term encompassing milk synthesis and release, but it does not specifically denote ejection.
Option D: Synthesis of milk is termed **galactogenesis**, not galactokinesis.

**Clinical Pearl / High-Yield Fact**
Oxytocin-induced milk ejection (galactokinesis) is crucial during breastfeeding; it is triggered by suckling and enhanced by maternal stimulation, and impaired function can lead to poor milk removal and engorgement.

✓ Correct Answer: C. Ejection of milk