Questions: Medical research indicates that vitamin A may be helpful in treating measles. If the research can be substantiated, the demand for vitamin A will increase. the supply of vitamin A will decrease. the demand for vitamin A will decrease. the supply of vitamin A will increase.

The answer is the demand for vitamin A will increase.

If medical research substantiates that vitamin A is helpful in treating measles, more people and healthcare providers will seek out vitamin A to use as a treatment. This increased interest and need for vitamin A will lead to a higher demand for the vitamin.

This option is less likely because the supply of vitamin A is not directly affected by the research findings. The supply would only decrease if there were production issues or other supply chain disruptions, which are not mentioned in the context of the question.

This option is incorrect because the research indicates a beneficial use for vitamin A, which would logically lead to an increase, not a decrease, in demand.

While the supply might eventually increase to meet the higher demand, the immediate effect of the research findings would be an increase in demand, not supply. Supply adjustments typically follow changes in demand.