If the price of electric bicycles decreases, the correct response is:
Quantity demanded will increase.
This is in accordance with the law of demand, which states that, all else being equal, as the price of a good decreases, the quantity demanded of that good increases. It's important to note that this refers to a change in quantity demanded rather than a change in demand, which would happen due to factors other than price (such as consumer preferences, income levels, etc.).