If this were the given choices:
a.debit to Tax Preparation Revenue for $9,800.
b.debit to Cash for $9,800.
c.credit to Tax Preparation Revenue for $9,800.
d.credit to Cash for $9,800.
My answer would be: C. CREDIT TO TAX PREPARATION REVENUE for $9,800
In the above problem, the revenue has already been earned but not yet collected. Thus, its corresponding adjusting entry would be a debit to a receivable account and a credit to an income account.
The receivable account would most likely be Accounts Receivable while the income account is the Tax Preparation Revenue account. The amount $9,800 is derived from 50 tax returns @ $196 each.