For the purpose of calculating GDP, investment is spending on
a. stocks, bonds, and other financial assets.
b. real estate and financial assets such as stocks and bonds.
c. capital equipment, inventories, and structures, including household purchases of new housing.
d. capital equipment, inventories, and structures, excluding household purchases of new housing.

c. capital equipment, inventories, and structures, including household purchases of new housing. 

Explanation:

Gross domestic product is the sum of all final goods and services produced in an economy within a given period which is usually a year.

GDP calculated using the expenditure approach:

Consumption spending + Investment spending by businesses + Government Spending + Net Export

Consumption spending is the amount spent by households on durable and non durable goods.

Investment spending is spending on capital equipment, inventories, and structures, including household purchases of new housing.

Government spending includes spending by government or an agency of the government.

Net Export is export less import.  

I hope my answer helps you

answer; by looking at total product,marginal product,and changes in both after changes in inputs

answerconversion factor;