Which of the following is a true statement regarding trans-saharan trade prior to the age of exploration? select one or more: a. for the most part, encounters between west africans and arabs were peaceful. b. commercial and cultural exchanges between the mediterranean and west africa didn't occur frequently until the 1400s. c. trans-saharan trade was only possible along one route, which was heavily guarded by muslim soldiers. d. west africans mainly traded weapons and horses for slaves and gold.