Changes in aggregate demand
a. are primarily based on changes in firms' abilities to produce products.
b. could be caused by changes in the spending decisions of the households, businesses, the government, and foreigners.
c. are unlikely to change quickly in response to economic events.
d. are not affected by changes in government policies.

The correct answer is option B.

Explanation:

The aggregate demand comprises of consumption spending, investment expenditure, government purchases, and net exports. It is a downward-sloping curve which is inversely related to the price level.  

Changes in aggregate demand are caused when there is a change in consumer spending, investment expenditure, government purchases or net exports, or all of them.  

This basically means that aggregate demand is affected by the spending decisions of the households, businesses, the government, and foreign consumers.

client registration system, resource management system, clinical management system, patient information database, common use-system interface

explanation: