Correct Answer : Option (A) :   RP-1
                                                                                                                
                                                                                                                                                                        
                                                        Explanation : RP-1 fuel is used in the first stage of Titan 1. Other than that, it was also used in the first stages of Saturn V, Energeia, Saturn I and IB etc. It is a cheaper and less explosive alternative to LH2.