Answer:
a. Interest rates rise and truck prices rise.
Step-by-step explanation:
Mixster Concrete Company are less likely to buy the truck if the interest rates rise and truck prices rise.
An increase in the interest rate means they would be paying more on the principal amount borrowed from any financial institution, thereby increasing their overhead costs.
Also, the sudden change in truck prices as against the initial rate would cause them not to buy so as not to have a budget deficit.