Explanation
Option (a) is incorrect: A fall in the price level (deflation) is not a direct result of increased demand for money with an unchanged supply. A fall in prices (deflation) is more likely to occur when there is a decrease in demand for money or an increase in the supply of money.
Option (b) is correct: When the supply of money remains constant and the demand for money increases, the equilibrium interest rate rises. This is because with higher demand and a fixed supply of money, individuals and businesses are willing to pay more for the same amount of money which leads to higher interest rates. The demand for money is inversely related to the interest rate: as interest rates rise, the cost of holding money increases, reducing the demand. Conversely, lower interest rates make holding money cheaper, increasing demand.
Option (c) is incorrect: A decrease in interest rates would occur if there was a decrease in the demand for money or an increase in the supply of money.
Option (d) is incorrect: Although changes in interest rates can influence economic activity, an increase in the demand for money with a constant supply primarily affects interest rates directly. The impact on income and employment depends on multiple other economic factors and is not an immediate consequence.