The correct answer is option 3: Flower buds. Cloves, which are commonly used as a spice, are derived from the dried flower buds of the clove tree (Syzygium aromaticum).

Option 1: Seeds are not the source of cloves. The cloves are not the seeds of the clove tree, but rather the flower buds.

Option 2: Fruits are also not the source of cloves. Cloves are not obtained from the fruit of the clove tree, but instead from the dried flower buds.

Option 4: Young leaves are also not the source of cloves. Cloves are not derived from the young leaves of the clove tree, but from the dried flower buds.

In summary, cloves are spice derived from the dried flower buds of the clove tree, making option 3 "Flower buds" the correct answer.