**Core Concept**
A submucosal fibroid is a type of uterine fibroid that grows into the uterine cavity, leading to heavy menstrual bleeding. The best treatment option depends on the size, location, and number of fibroids, as well as the patient's age, parity, and desire for future fertility.

**Why the Correct Answer is Right**
Hysteroscopic myomectomy is the most appropriate treatment option for this patient because the fibroid is submucosal and causing heavy menstrual bleeding. This procedure involves removing the fibroid through the cervix using a hysteroscope, which is a minimally invasive approach that preserves the uterus and allows for future fertility. The patient's age, parity, and desire for future fertility also make this option more suitable. Additionally, hysteroscopic myomectomy has a shorter recovery time compared to other surgical options.

**Why Each Wrong Option is Incorrect**
**Option A:** GnRH injection (leuprolide acetate) is used to treat uterine fibroids by inducing a temporary menopausal state, which can shrink the fibroids. However, it is not a definitive treatment and may not be suitable for patients with heavy menstrual bleeding due to its potential side effects, such as hot flashes and vaginal dryness.

**Option B:** Uterine Artery Embolization (UAE) is a minimally invasive procedure that involves blocking the blood supply to the fibroid, causing it to shrink. However, it may not be effective for submucosal fibroids and can lead to complications such as ovarian failure and menopausal symptoms.

**Option D:** Laparoscopic myomectomy is a surgical procedure that involves removing the fibroid through small incisions in the abdomen. While it is a viable option for patients with multiple fibroids or larger fibroids, it may not be the best choice for a single submucosal fibroid, especially in a patient who desires future fertility.

**Clinical Pearl / High-Yield Fact**
Hysteroscopic myomectomy is a highly effective treatment option for submucosal fibroids, with a high success rate and minimal complications. It is essential to evaluate the size, location, and number of fibroids, as well as the patient's medical and surgical history, to determine the best treatment option.

✓ Correct Answer: C. Hysteroscopic myomectomy