Your rear window is completely blocked by cargo, so you can't see through it at all. Does HTA Section 74 allow you to keep driving?

Correct answer: B. Yes — as long as properly positioned mirrors give a clear view of the road behind

Section 74(1) generally requires a clear view through the rear window, but 74(2) creates a specific exception: if the vehicle has properly positioned and maintained mirrors that give the driver a clearly-reflected view of the road behind, the rear window itself doesn't need to be clear. This is why vans and loaded pickup trucks with a fully blocked rear window are still legal to drive, as long as their mirrors do the job.

Source: MTO Driver's Handbook: Highway Traffic Act, Part VI (Equipment) — Section 74, windows to afford clear view