Answer:
The answer is B. vertical, because buyers purchase the same amount as before whenever the price rises or falls
Explanation:
When demand is perfectly inelastic, the demand is not sensitive to price. The consumers' quantity demanded stays costant or or remain the same with a fall or rise in demand.
The elasticity is always less than one. Necessity goods are in this category. They are needed almost everyday. For example, electricity, water are part of humans' daily needs.