Which one is "on" at zero gate voltage? The honest answer is: it depends which MOSFET you're holding — and assuming the wrong one is a real design mistake.
Almost every MOSFET most engineers meet — in digital logic, in switching power supplies, in the vast majority of modern ICs — is off with no gate voltage applied, and needs the gate driven past a threshold to switch on. That experience quietly becomes an assumption: "MOSFETs are off until you turn the gate on." It's not universally true. A second, less common family of MOSFET is built to be already conducting the moment it's powered up, with no gate signal at all — and gate voltage is used to turn it more off, not more on. Same three terminals, same basic device physics, opposite default behavior.