How does the rule of conservatism apply to asset impairment?

It allows assets to be written up when their value increases substantially above book value in market conditions.

It mandates that all assets be depreciated at the same rate annually regardless of type or condition.

It requires all assets to be revalued annually by independent management teams for accuracy and compliance.

It requires assets to be written down when their value decreases, but not written up when their value increases.