I want to know the answer to the following question:
How many military services beling to the Department of Defense?
All the background I'm provided with is that "In 1986, the Goldwater–Nichols Act mandated that operational control of the services follows a chain of command from the President to the Secretary of Defense directly to the unified combatant commanders, who have control of all armed forces units in their geographic or function area of responsibility.". Is that enough to answer the question?
Answer: no