b.seven-day is the correct answer
Answer:
Caves, caverns, sinkholes, funnel-shaped holes, underground rivers and lakes
Explanation:
The karst topography is found at places that are dominated by rocks made out of calcium carbonate, better known as limestone. These rocks react with the water very easily and get dissolved from it very easily. Because of the large scale dissolving, this type of topography has numerous specific features. Some of the most common features in the karst topography are the caves, sinkholes, caverns, funnel-shaped holes, underground rivers, underground lakes etc. All of them are very attractive and understandably cause a lot of interest, thus they are often tourist destinations, but more importantly of big scientific interest. The biggest problem with this topography is that it is generally not stable, and it is very common that the rocks can crumble, which makes them relatively dangerous if visited at certain periods of the year, especially when there is more precipitation.
Many people go bling in North Korea because of its most basic medical facilities
Clouds are created when water vapor turns into water droplets. Water droplets are tiny particles that float in the air.
Cumulus - Fluffy clouds that have flat bases
Cirrus - Short detached hair like clouds that are found at high altitudes
Nimbus - Cloud that has rain or snow falling from it
Stratus - Flat featureless clouds that are found at low altitudes
