Question

all of the following are nonlegislative powers except _____. investigative powers enforcement powers impeachment powers executive powers

Answer 1

I believe the answer is:  enforcement powers 

Non-legislative powers refers to the power that is not related to the process of making law. 
Enforcement power is the power for congress to propose amendment's provisions by appropriate legislation, which is related to the process of creating new law

Answer 2

The answer is Enforcement Powers. Non-legislative powers or non-legislative functions are powers and responsibilities not directly related to the process of making new laws, which include Include impeachment power, executive power, investigative power.