I agree with Brandon about looking at the books / authors the agents represent. I don't agree that you should email them and ask them which agent. I wouldn't think that this would receive a reply.
Do each of the agents have their own email address? Usually, when I see something like what you describe, there is just one slush pile email address for queries. Perhaps they don't want you to specify an agent in email queries.
Another tactic that I've found useful is to bing something like, "[exact agent's name] literary agent blog", or "[exact agent's name] literary agent interview". Not only will this help you to appropriately personalize your query letter, you will probably find out in these interviews exactly what the agent is looking for.
hth