Answer:
D:The supply of guitars will increase
Explanation:
Tin is one of the materials needed to make a guitar. If the tin price decrease, the cost to make a guitar will also decrease. If the cost of guitar decrease, the producer can get more profit by selling a guitar so they will try to make more. This lead to an increased supply of guitar. Some producers will sell the guitar at a lower price too, make more people can buy it and the demand will increase. It is not stated if silver can substitute tin and if it's cheaper, so we can't draw a conclusion on it.
