What is market demand?

a. The subtraction of the individual quantities demanded by each buyer in a market at each price.
b. The addition of the individual prices of the product at each level of quantity.
c. The multiplication of the prices of each product by the individual quantities demanded by each buyer in a market.
d. The division of the total spending by an individual buyer by the prices paid for the product.
e. The addition of the individual quantities demanded by each buyer in a market at each price