NEET UG CHEMISTRY MCQ: THERMODYNAMICS

Given:
i) $C\left( {\mathrm{graphite}} \right) + {O_2}\left( g \right) \to C{O_2}\left( g \right);\,\,\,\,{\Delta _r}{H^{ \cdot \cdot }} = x\,\,\,kJ\,\,\,mo{l^{ - 1}}$
ii) $C\left( {\mathrm{graphite}} \right) + \frac{1}{2}{O_2}\left( g \right) \to C{O_2}\left( g \right);\,\,\,{\Delta _r}{H^{ \cdot \cdot }} = y\,\,kJ\,\,mo{l^{ - 1}}$
iii) $CO\left( g \right) + \frac{1}{2}{O_2}\left( g \right) \to C{O_2}\left( g \right);\,\,\,\,{\Delta _r}{H^{ \cdot \cdot }} = z\,\,kJ\,\,mo{l^{ - 1}}$ Based on the above thermochemical equations, find out which one of the following algebraic relationships is correct?