The correct answer is:
A demand curve is a graph that has on the y-axis the demand for that product and on the x-axis its price and it demonstrates the quantities of stores demanded at each price by consumers.
For example: if the price of the product falls, this product is preferable to look for other alternatives, that have now become more expensive or can simply buy larger quantities of that product; thus, consumer demand for this product increases. Likewise, if price increases, demand will drop if all other things are equal.