Taxpayer, Morgan, is a single individual with $20\backslash$times $3$ taxable pension income of $$18,000,$ tax exempt interest income of $$10,000,$ and Social Security benefits of $$9,000.$ How much of the Social Security benefits will be taxable on Morgan's $20\backslash$times $3$ federal income

A$.$ $$7,650$

B$.$ $$4,500$

C$.$ $$6,410$

D$.$ $$1,910$

E$.$ None of the above