[单选题]
Cracking is a process by which gaseous alke( 08g x zbj3wgyb3i*panes are converted to smxf nv*9sao57z(w dk (zaller-chain alkanes and alkenes.(zownf x 75zk(s9 a*vd One possible reaction in the cracking of butane is shown.
What is the enthalpy change of the cracking reaction?
A. +80kJ mol$^{-1}$
B. +150kJ mol$^{-1}$
C. -80kJ mol$^{-1}$
D. -150kJ mol$^{-1}$