Answer: A. competition among producers
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Explanation:
Competition reduces prices while also increasing the quality of the product or service. Companies that don't do such things will likely be out of business since the customer can go elsewhere for a better experience. The more competition, the better consumers are off.
In contrast, monopolies are bad for consumers because one company can set the price to whatever they want (to a certain level of course) and the customer has no choice to pay that price. The customer does not have any other option so the company is in full control. This leads to decline in quality because quality is often associated with cost. Safety standards may decline as well. So this is why monopolies are not good for the customer. In cases where there are monopolies, such as with power utilities, it is strongly advised that government regulations are put in place. This way the company doesn't completely exploit the customer.
In short, we can eliminate choice D because it runs counter to choice A.
Choice C can also be eliminated because if you had a decrease in supply, then the price of the product is likely to go up if you hold other factors in check (such as keeping the same level of demand). Higher prices do not benefit consumers unless those consumers had an equal or better wage increase.
A raise in interest rates means that it becomes more expensive to borrow money. For example, a raise in interest rates means that mortgage rates go higher. This negative is slightly counterbalanced with the fact that savings accounts interest rates go up as well. Overall, I think a rise in interest rates means that consumers ultimately pay more, so we can cross choice B off the list as well.
