A Java class, Database, contains a public method called printStatistics, which outputs statistical information related to that database. The printStatistics method calls another helper method, calculateMean, which is only ever used in this context $-$ it is never called from outside the Database class.

Declaring the calculateMean method with the public access modifier would be bad program design, as it is an example of$...$

a$.$ Low method cohesion.

b$.$ Explicit coupling.

c$.$ Implicit coupling.

d$.$ Low class cohesion.