Which of the following is an example of the idea of "separation of powers" in the American constitutional system?

Each state elects representatives and senators to Congress.
The process for creating laws involves Congress and the president.
The military is allowed to make decisions without the president's approval.
Congress is allowed to pass laws without approval of the president.

The correct example of the idea of "separation of powers" in the American constitutional system is: The process for creating laws involves Congress and the president.

This exemplifies the separation of powers as it shows that both the legislative branch (Congress) and the executive branch (president) are involved in the lawmaking process. The president can either sign or veto bills passed by Congress, creating a system of checks and balances.