The correct answer is A. Inelastic demand.
Inelastic demand is a situation in which the demand for a good or service is relatively unresponsive to changes in price. This means that if the price of a good or service increases, consumers will not decrease their demand for it by very much. Conversely, if the price of a good or service decreases, consumers will not increase their demand for it by very much.
In the case of the question, an increase of 50% in the price of a commodity causes a decrease in its demand by only 10%. This indicates that the demand for the commodity is inelastic.
There are a number of factors that can affect the elasticity of demand for a good or service. These include the availability of substitutes, the necessity of the good or service, and the time horizon.
The availability of substitutes is one of the most important factors that affects the elasticity of demand. If there are many substitutes available for a good or service, then consumers will be more likely to switch to a substitute if the price of the good or service increases. This will make the demand for the good or service more elastic.
The necessity of a good or service is another important factor that affects the elasticity of demand. If a good or service is essential, then consumers will be less likely to reduce their demand for it even if the price increases. This will make the demand for the good or service less elastic.
The time horizon is also an important factor that affects the elasticity of demand. In the short run, consumers may be less likely to change their consumption habits in response to a change in price. This is because they may not have time to find substitutes or to adjust their budgets. In the long run, however, consumers are more likely to change their consumption habits in response to a change in price. This is because they will have more time to find substitutes and to adjust their budgets.
In conclusion, the correct answer to the question is A. Inelastic demand.