The correct answer is: D. Both (A) and (R) are correct but (R) does not offer a full explanation of (A)
Assertion (A) is correct because, in general, a decrease in price will lead to an increase in demand. This is because a lower price makes the good more affordable, which will encourage more people to buy it.
Reason (R) is also correct because, if the price of a good decreases, some people who were previously not able to afford it may now be able to buy it. However, this is not the only reason why demand might increase. For example, if the price of a good decreases, people may also buy more of it because they believe that it is a good deal.
Therefore, both (A) and (R) are correct, but (R) does not offer a full explanation of (A).