Can anyone help me with this question

Quinn Co reported a net deff tax asset of $9k in 12/31/09 balance sheet.  For 2010 it reported pretax FS income of $300k.  Temp diff of $100k resulted in taxable income of $200K for 2010. At 12/31/10 Quinn had cumulative taxable differences of $70K.  Quinn's Eff tax rate is 30%.  In its 12/31/10 Income statement, what should Quinn report as def. income tax expense

a 12k

b 21k

c 30k

d 60k

Why is the answer C instead of B?  I thought the deferred expense was the change during the year DTA and DTL.  30-9?

And what does the cumulative taxable differences of $70K mean?

The entry to record the deferred tax asset in 2009 included temporary differences of $30,000.

The 9,000 is the 30% tax effect of those differences.

DR: Deferred tax asset 9,000

CR: Deferred tax expense (9,000)

The entry to record the 2010 tax expense:

DR: Current tax expense 60,000 (200,000 * 30%)

DR: Deferred tax expense 30,000 (100,000 * 30%)

CR: A/P (60,000)

CR: Deferred tax liability (30,000)

Cumulative taxable differences = 70,000

1.  Taxable difference from 2009 = 30,000 (Asset)

2.  Taxable difference from 2010 = (100,000) (Liability)

3.  Balance = (70,000) (Liability)