Answer:
The correct answer is option c.
Explanation:
A market demand curve shows the quantity demanded at different prices by all individuals. It is the summation of individual demand curves.
The downward-sloping curve shows the relationship between the price level and the quantity demanded. That when the price level increases, the quantity demanded decreases and vice versa. The other factors such as population, income, price of other goods, tastes and preferences are assumed to be constant.