Random Guessing... likely answer choice?

Every answer choice has an equal chance of being correct, so there's really no "best guess". My advice is to pace yourself so that you have at least 30 seconds to give a quick look at the answers and eliminate one or two that you know are clearly incorrect (often easy to do on verbal, since some of the SC have glaring errors and some of the RC and CR have answers that are clearly outside the scope of the passage).