Multi-select problem: How does the next paragraph end?

How to keep discus
Keep a clean tank.
Discus fish are sensitive to disease and water conditions. They don't like water changes well.

pick from the following.
(a). No matter how frequently you change your tank, a large tank will get dirty faster than a small one. If possible, try to keep a clean tank for each substrate you remove.;
(b). If you water your fish once a week on a regular basis, you should keep your tank healthy. If your water changes too quickly, keep it clean.;
(c). It is recommended that you have one fish per ten gallons. Make sure the ph level is between 6 and 7; levels below 6 and above 7 will cause discus stress.;
(d). Please stay up to date on their specific needs. Replace normal or natural tap water with aquarium water.;
(c).