The correct answer is B) The ships were at the mercy of the weather.
The explanation that best describes why the transatlantic journey of the Middle Passage took longer than the expected time in some instances is "The ships were at the mercy of the weather."
The Middle passage was the name given in the 16th century to the unhuman transportation of slaves from Africa to America. Historians believe that almost 12 millions of Africans were taken to be used as slaves in the Americas from the 16th century to the 19th century. This period in history is also known as the Transatlantic Slave Trade. The Middle passage was the second part of the slave trade that went from Europe to Africa (first leg), the Middle Passage (second leg) and the Americas to Europe (third leg). The ships had delays because they were at the mercy of the weather and during the trip, many slaves died due to the inhuman conditions.