A Schedule B of Form $941$ is required in which of the following situations?

a$.$ The employer is a monthly depositor.

b$.$ An employer who is a semiweekly depositor

c$.$ A new employer who is subject to the $$100,000$ next$-$day rule on their fourth payroll

d$.$ Both "a new employer who is subject to the $$100,000$ next$-$day rule on their fourth payroll" and $"$an employer who is a semiweekly depositor" are correct.