How are muslims history and christians history similar?

Christianity and Muslim idealogies are patterned with some similarities. Both of them believe that there's one God that must be worshipped with utmost holiness. As they are both monotheistic and both Abrahamic in origin, Christians and Muslims share common practices such as honoring the bible (Quran;Islam: Holy Bible;Christianity), celebrating holy day of obligation (Ramadan;Islam: Feast of Holy Saints: Christianity)and believing into a so called " salvation" which emphasizes how strong their faith is to their Creator (Allah; Islam: God; Christianity). These are some of the histories that prove that both religions have same origins, principles about their practices and belief of Eternal Happiness with the Creator which is the salvation.   

Ibelieve the answer is b cause its only saying what they were focusing on,not a hardship