Answer to Question 1
The throat, mouth, and tongue will become red and inflamed (glossitis), and the lips will become dry and scaly. Milk is an excellent source of riboflavin.
Answer to Question 2
An appropriate experiment would involve two groups of individuals of the same sex and age. All individuals are exposed to cold viruses via inhalation. They then are divided into two groups: an experimental group that receives identical doses of vitamin C supplements and a control group that gets a placebo. The experiment is double-blind. Signs and symptoms of both groups are tracked over 10 days. After data collection and analysis, conclusions are made as to whether the vitamin C had an effect on the cold.