**Core Concept**
The question pertains to the management of cervical cancer, specifically focusing on radiation therapy dosages. **Radiation oncology** principles guide the treatment of cervical cancer, with careful consideration of doses to minimize damage to surrounding healthy tissues.

**Why the Correct Answer is Right**
In the context of cervical cancer treatment, particularly for early and advanced stages, the maximum radiation dose to point A is a critical consideration. Point A is defined as a reference point 2 cm lateral to the external cervical os and 2 cm superior to the external cervical os, representing the paracervical triangle where the uterine arteries cross the ureters. The dose limitation at this point is essential to avoid complications such as radiation cystitis, proctitis, and fistula formation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underestimates the dose required for effective treatment of cervical cancer.
**Option B:** This option overestimates the safe dose, potentially leading to increased toxicity.
**Option D:** This option is also incorrect as it does not align with established guidelines for radiation doses in cervical cancer treatment.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the dose to point A should not exceed 90 Gy for combined external beam radiation therapy (EBRT) and brachytherapy in the treatment of cervical cancer. This dose limitation helps in minimizing the risk of severe side effects.

**Correct Answer:** D. 90 Gy