Which of the following method(s) can be used so that water can be made safe for drinking?

All of these

The correct answer is option 4. All of these.

A popular household filter is a candle type filter. This is a physical method of removing impurities. 

Many households use boiling as a method for obtaining safe drinking water. Boiling kills the germs present in the water.

Chlorination is a commonly used chemical method for purifying water. It is done by adding chlorine tablets or bleaching powder to the water. We must be cautious. We should not use more chlorine tablets than specified.