Which of the following can explain the upward slope of the short-run aggregate supply curve? a. nominal wages are slow to adjust to changing economic conditions b. as the price level falls, the exchange rate falls c. an increase in the money supply lowers the interest rate d. an increase in the interest rate increases investment spending

A - nominal wages are slow to adjust to changing economic conditions 

Explanation:

In the short run, the costs of many of the factors used in the production process are fixed.  For example labours wage is fixed for a number of years because of labour contracts. Also the raw materials used in the production process have long term agreements that fix their prices.

As a result of factors of production been fixed in the short run, when general price level rises and the cost of production remains constant, profit also rises.

Firms take advantage of this rise in price and increase production and the quantity of aggregate supply increases. This is why the short run aggregate supply curve is upward sloping.

answer; monopolistic competition;