**Core Concept:** The B. Lynch suture is a surgical technique used to control massive postpartum hemorrhage (PPH). It involves placing a deep horizontal mattress suture through the liver and the uterine wall to create a compressive effect and control bleeding.

**Why the Correct Answer is Right:** The B. Lynch suture is applied on the liver because it is the largest and most accessible abdominal organ, which provides significant compression when sutured. The deep horizontal mattress suture allows for secure placement and multiple bites, ensuring adequate compression and haemostasis.

**Why Each Wrong Option is Incorrect:**

A. **Incorrect Structure:** Placing the suture on the spleen would not be effective as the spleen is not as large or accessible as the liver.

B. **Incorrect Technique:** Applying the suture on the diaphragm would not provide adequate compression due to the thin diaphragmatic membrane and lack of depth for secure suturing.

C. **Incorrect Structure:** Placing the suture on the stomach would not be effective because the stomach is thin-walled and not as large as the liver or spleen.

D. **Incorrect Structure:** Suturing the skin would not control PPH as it is the internal organs and their relationship that provide compression and haemostasis.

**Clinical Pearl:** B. Lynch suture is a valuable life-saving technique for managing severe postpartum haemorrhage when other interventions fail. Adequate knowledge and skill in performing this suture can significantly reduce maternal mortality rates.

**Correct Answer:** C. Liver