**Core Concept**
When selecting a screening test for a disease, several factors need to be considered to ensure the test is effective, efficient, and beneficial for the population being screened. These factors include the cost of the test, the efficacy of the treatment available for the disease, the prevalence of the disease, and the potential suffering or impact of the disease on the affected individuals.

**Why the Correct Answer is Right**
Knowledge of the physician about the disease is not a crucial factor in selecting a screening test. The decision to implement a screening program should be based on scientific evidence, not personal opinions or biases. A physician's knowledge of the disease may influence their individual clinical decisions, but it should not be the primary consideration when selecting a screening test for a population. The selection of a screening test should be based on factors that can be quantified and evaluated, such as cost-effectiveness, sensitivity, and specificity.

**Why Each Wrong Option is Incorrect**
**Option A:** While the cost of the test is an important consideration, it is not the only factor that should be considered. Cost-effectiveness is a crucial aspect of screening test selection, but it should be weighed against other factors such as the efficacy of the treatment and the prevalence of the disease.

**Option B:** The efficacy of the treatment available for the disease is a critical factor in selecting a screening test. If the treatment is ineffective or has significant side effects, it may not be worth implementing a screening program. Therefore, this option is incorrect because it is an important consideration.

**Option D:** The potential suffering or impact of the disease on affected individuals is a significant consideration in selecting a screening test. Screening tests are often implemented to reduce morbidity and mortality from a particular disease. Therefore, this option is incorrect because it is an important factor in the decision-making process.

**Clinical Pearl / High-Yield Fact**
When selecting a screening test, consider the "ABCs": Availability, Benefits, and Costs. Ensure that the test is available, provides significant benefits to the population being screened, and is cost-effective.

**✓ Correct Answer: C. Knowledge of the physician about the disease**