Earnest money in a real estate transaction serves to:

A is incorrect because earnest money does not pay the agents' commission. Commissions are typically paid separately from earnest money, usually at closing from the sale proceeds, not from the buyer's deposit.

C is incorrect because while earnest money may be applied toward closing costs in some cases, this is not its primary purpose. Closing costs are typically paid separately and include various fees beyond just the earnest deposit.

D is incorrect because earnest money does not pay the seller's mortgage. The mortgage is the seller's personal obligation that must be satisfied separately from the earnest money deposit.