please provide explanation with the correct option

When must a partnership make mandatory basis adjustments? A) on any sale of a 20% or greater partnership interest B) on any sale of a partnership interest for $250,000 or more C) on any distribution of assets with a value of $250,000 or more D) on any sale of a partnership interest where the partnership's adjusted basis in its assets exceeds their fair market value by $250,000 or more