Alinor is a coastal town situated on a high bay. Dolphins migrate to Alinor Bay annually to breed. This natural phenomenon has become a major tourist attraction. During the breeding season the dolphins are very sensitive to light and sound. The Alinor community has always taken care to keep the noise level down in the bay area during the breeding season. Davy decides to open a karaoke club in the town. The community wants to close down the karaoke club because they are afraid that the pulsating music and flickering lights will discourage the dolphins from migrating to Alinor Bay to breed. Davy avers that there is no legislation which restricts noisy business activities in the Alinor Bay area.

Consider the following:

The court will acknowledge the validity of the Alinor community's customs if the community can, amongst other things, prove that the prohibition on noise __________.

A has existed for a long time.

B has been put in writing.

C will encourage the breeding of dolphins.

D is certain and clear.

Which of the above are CORRECT?