**Core Concept**
Mitomycin-C is an antineoplastic antibiotic that has been used as an adjunct in trabeculectomy to prevent scarring and promote the success of the procedure. It works by inhibiting the action of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) synthesis in fibroblasts, thereby reducing the formation of scar tissue.

**Why the Correct Answer is Right**
Mitomycin-C is applied topically during trabeculectomy to create a bleb by inhibiting the proliferation of fibroblasts and subsequent scarring. This allows for the formation of a patent filtration pathway, facilitating the drainage of aqueous humor from the anterior chamber. The mechanism of action of Mitomycin-C involves the inhibition of DNA synthesis in fibroblasts, which are the cells responsible for the production of scar tissue.

**Why Each Wrong Option is Incorrect**
**Option B:** Azathioprine is an immunosuppressive agent that works by inhibiting the synthesis of purines, but it is not used in trabeculectomy to prevent scarring. It is primarily used to prevent transplant rejection and in the treatment of autoimmune diseases.
**Option C:** Cituximab is not a recognized pharmaceutical agent, and it is unlikely that this option is correct. However, it is worth noting that cetuximab is a monoclonal antibody that targets the epidermal growth factor receptor (EGFR) and is used in the treatment of certain cancers. It is not used in trabeculectomy.
**Option D:** Ketorolac is a nonsteroidal anti-inflammatory drug (NSAID) that is used to reduce pain and inflammation, but it is not used in trabeculectomy to prevent scarring.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the use of Mitomycin-C in trabeculectomy is off-label, and its use should be carefully considered to minimize the risk of complications. The ideal concentration and duration of application of Mitomycin-C are still being debated, and further research is needed to optimize its use in this context.

**✓ Correct Answer: A. Mitomycin-C**