Concept:A balanced meal must include carbohydrates, proteins, fats, vitamins, minerals, and fibre in proper proportions.
Explanation:Yam mainly supplies carbohydrates.
Vegetables mainly supply vitamins, minerals, and fibre.
Such a meal lacks an adequate source of proteins.
Proteins are essential for growth and repair of body tissues.
Therefore, this meal is not balanced because it does not contain proteins.
Answer:B. proteins