Which one below in relation to the concept of materiality is not correct?

a.

An amount that is equal to or less than 5% of the appropriate base amount is presumed not to be material.

b.

An amount that is equal to or greater than 10% of the appropriate base amount is presumed to be material.

c.

whether an amount between 5% and 10% is material is a matter of judgment.

d.

The higher the risk, the higher the materiality an auditor uses.