HK Ltd's Balance Sheet at 30 June 2015 Disclosed the Following

HK Ltd's balance sheet at 30 June 2015 disclosed the following.
$
Buildings 450 000
Less accumulated depreciation 120 000
330 000
On 1 July 2015 the director of HK decided to revalue the buildings to a fair value of $400 000.The general journal entry to record the revaluation is which of the following?

A) Debit gain on revaluation $70 000; credit buildings $70 000
B) Debit accumulated depreciation buildings $70 000; credit gain on revaluation $70 000
C) Debit accumulated depreciation buildings $120 000; credit gain on revaluation $70 000; credit buildings $50 000
D) Debit accumulated depreciation buildings $120 000; credit income account $70 000; credit buildings $50 000