Which of the Following Statements Is the Best Description of 'Unascertained

Which of the following statements is the best description of 'unascertained' goods?

A) Goods that are defined by description only, such as 'A bag of apples.'
B) Goods identified and agreed upon at the time of sale, such as 'This apple.'
C) Goods to be manufactured or acquired by the seller after the time of sale, such as 'Your next crop of apples.'
D) Goods which were previously unascertained but have now been identified and agreed upon by the parties, such as 'I accept your selection of apples in this bag.'