Which of the following statements is/are correct?

a. Bamboo pipes are used to divert perennial springs on hilltops to the lower reaches by gravity in the bamboo drip irrigation system. b. This is a newly popular system of tapping stream and spring water. c. About 18-20 litres of water enters the bamboo pipe system, gets transported over hundreds of metres and finally reduces to 20-80 drops per minute at the site of the plant.