<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 33-year-old woman presents to her physicians office for a postpartum check-up. She gave birth to a 38-week-old boy via an uncomplicated vaginal delivery 3 weeks ago and has been exclusively breastfeeding her son. The hormone most responsible for promoting milk let-down during lactation in this new mother would lead to the greatest change in the level of which of the following factors?? A: cAMP, B: cGMP, C: IP3, D: Ras, E: Phospholipase A,  <response>: This is a question about the hormonal regulation of lactation. The key information in the stem is that the patient is a postpartum woman who has been exclusively breastfeeding her newborn son. The question asks about the hormone most responsible for milk let-down during lactation. Based on this information, the hormone of interest is oxytocin. Oxytocin is released from the posterior pituitary in response to suckling and stimulates contraction of myoepithelial cells surrounding the mammary alveoli to cause milk ejection. The choices list various second messengers and signaling molecules. To determine which one is most directly affected by oxytocin signaling, we need to consider the mechanism of oxytocin receptor activation. Oxytocin receptors are Gq coupled receptors, which activate phospholipase C and lead to IP3 production and intracellular calcium release.Therefore, the answer is likely to be IP3. Lets evaluate the choices:A cAMP - not directly affected by oxytocin signaling B cGMP - not directly affected by oxytocin signalingC IP3 - increased by oxytocin receptor activation of phospholipase CD Ras - not directly affected by oxytocin signalingE Phospholipase A - not directly activated by oxytocin receptorsC: IP3 