A company rented office space to a tenant on January 1 and received a total of $90,000 for the first nine months of rent. The amount was recorded as Rent Collected in Advance when received. Adjustments are recorded only at the end of every quarter. What effect does the adjustment at March 31 have on the company's net income for the quarter ending March 31?

a. Increase by $90,000

b. Decrease by $30,000

c. Decrease by $60,000

d. Increase by $30,000