The task is to develop a simple web page with three drop downs. The first drop down contains the list of continents in the world, second contains the list of countries, and the third contains the cities.

When the page is loaded first, the first drop down contains the list of continents and the other two drop downs do not contain anything.

When the user selects a continent, the second drop down should be populated to have the list of countries in that particular continent, still the third drop down doesn't contain anything.

When the user selects a country, the third drop down should be populated to have the list of cities in that particular country.

The idea is that the second and third drop downs should be populated dynamically.