If the Reserve Bank of Australia buys financial securities,$,$ this ________.$\_\_\_\_\_\_\_\_.$

a.$.$

increases reserves, causes banks to reduce their loans, and decreases interest rates

b.$.$

increases reserves, decreases interest rates, and encourages banks to make more loans

c.$.$

decreases reserves, increases interest rates, and encourages banks to make more loans

d.$.$

decreases reserves, causes banks to reduce their loans, and increases interest rates