The correct answer is (B) To negotiate, particularly over a small matter; to swap or trade by petty bargaining; to barter; to bargain; to haggle.

Dicker possibly comes from German decher (trading unit).

Examples of use:

• He dickered for a half hour over the quantity of gasoline to be included.
• With the main issues already resolved, they used their remaining time to dicker over a few minor aspects of the contract.