For cracking propane, what compound Y( alkene) will we obtain?

Question

For cracking propane, what compound Y( alkene) will we obtain?

Answer 1

I would guess ethylene (ethene) - C2H4, with methane being the other product.

Answer 2

Cracking NORMALLY means splitting the chain. In that regard only ethene can form + CH3-X. But cracking can also mean just splitting off some fragment; thus propene can also form + H-X.