Which of the Following Reasons Best Captures Why Working with the IRB

Which of the following reasons best captures why working with the IRB can seem frustrating to researchers who are seeking to work on a collaborative project?

A) Not all institutions within the USA have IRBs, and if you are working with someone who does not have an IRB that governs the institution, the research collaboration is impossible.
B) Different IRBs across the nation have variations in their requirements, which makes meeting all of them sometimes difficult.
C) IRBs fight over which institution's guidelines should apply for the study, because collaborations only require 1 central IRB protocol to be approved
D) Researchers need to decide to which IRB to submit their application.