Why can there be a slight delay before air pressure fully reaches the brakes on the last trailer of a triples combination?

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1. Air has to travel through every connection point along the combination, and each one adds a small amount of lag
2. There is never any delay regardless of combination length
3. The delay only happens if the tractor's engine is off
4. The last trailer's brakes are electric, not air powered, unlike the rest of the combination and needs a completely different type of check

Correct!

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