**Core Concept**
Intravesical therapy involves delivering medications directly into the bladder to treat bladder cancer. For superficial bladder cancer, the goal is to eradicate cancer cells while minimizing side effects. Bacillus Calmette-Guérin (BCG) is a type of immunotherapy that uses a weakened form of the tuberculosis bacterium to stimulate the immune system to attack cancer cells.

**Why the Correct Answer is Right**
BCG works by stimulating the immune system to produce cytokines, which activate immune cells to recognize and attack cancer cells. This process is mediated by the activation of antigen-presenting cells, such as dendritic cells, which present antigens to T-cells. The T-cells then recognize and attack cancer cells expressing those antigens. BCG has been shown to be more effective than other intravesical therapies, such as mitomycin C and epirubicin, in preventing recurrence and progression of superficial bladder cancer.

**Why Each Wrong Option is Incorrect**
* **Option A:** Mitomycin C is a chemotherapeutic agent that works by inhibiting DNA synthesis, but it is less effective than BCG in preventing recurrence and progression of superficial bladder cancer.
* **Option B:** Epirubicin is a chemotherapeutic agent that works by intercalating DNA, but it is also less effective than BCG in preventing recurrence and progression of superficial bladder cancer.
* **Option D:** Docetaxel is a chemotherapeutic agent that works by inhibiting microtubule dynamics, but it is not commonly used as an intravesical therapy for superficial bladder cancer.

**Clinical Pearl / High-Yield Fact**
BCG is the most effective intravesical therapy for superficial bladder cancer, but it can cause side effects such as dysuria, urgency, and hematuria. Patients should be closely monitored for these side effects, and BCG should be discontinued if they occur.

**Correct Answer:** C. BCG.