Concept:The obligatory (fard) rak'ah for Zuhr, Asr, and Isha are added to find the total.Explanation:Zuhr has 4 obligatory rak'ah.Asr has 4 obligatory rak'ah.Isha has 4 obligatory rak'ah.Therefore, total rak'ah =4+4+4=12.Answer:The total number of rak'ah in Zuhr, Asr, and Isha is 12.Correct option: D. 12.