The Balance Sheet of Brown Ltd at 31 December 2014

The balance sheet of Brown Ltd at 31 December 2014 shows the following.
$
Plant 50 000
Accumulated depreciation - plant 30 000
20 000
On 1 January 2015,based on a valuer's estimate of fair value,it was decided to revalue the plant to $35 000.This was the first time the asset had been revalued.
The journal entry to record the revaluation is which of the following?

A) Accumulated depreciation - plant 30 000 Plant 15 000
Gain on revaluation plant 15 000
B) Plant 15 000 Gain on revaluation plant 15 000
C) Expense on revaluation of plant 15 000 Plant 15 000
D) Plant 15 000 Expense on revaluation of plant 15 000
Accumulated depreciation - plant 30 000