A block slides with negligible friction down a ramp. What is Kf − Ki = Delta K

A block slides with negligible friction down
a ramp, a distance L along the ramp. The
ramp makes an angle Theta with the floor. Its
initial kinetic energy is Ki, and after it has
moved a distance L its kinetic energy is Kf .
What is Kf − Ki = Delta K?

1. mg L sin Theta
2. mg L cos Theta
3. −mg L / tan Theta
4. mg L
5. Zero

I want to say it's 5. Zero because I've read somewhere that if there is no friction then the work is zero. But since I'm not completely sure, I'd like to ask the community first.

change in KE = - change in PE = mgLsin(theta). This is true ONLY if friction is negligibly small.
Choice 1