Which of the following describes the difference in stimuli required to detect a difference between the stimuli?

What is the difference between the kurds and the shia muslims? a the kurds are a religious group while the shia muslims are an ethnic group. b the kurds and the shia muslims are religious groups. c the kurds are an ethnic group and the shia muslims are a religious group. d the kurds and the shia muslims are ethnic groups.