Choice "A" is correct. If demand is perfectly inelastic (or not price sensitive), there will be no change in quantity demanded for a change in price. This means that consumers of the product will demand a constant quantity, regardless of the price. If the quantity supplied is reduced (presumably below an equilibrium point where supply equals demand), there will be excess demand for the product and sales price will go up. The increase in sales price will have no impact on demand (because demand is assumed to be perfectly price inelastic).
Choices "b", "c", and "d" are incorrect, per the above explanation.