The Owners of an Industrial Plant Want to Determine Which $H _ { 0 } : \left( \mu _ { e } - \mu _ { g } \right) = 0$

The owners of an industrial plant want to determine which of two types of fuel (gas or electricity) will produce more useful energy at a lower cost. The cost is measured by plant investment per delivered quad ($ invested /quadrillion BTUs). The smaller this number, the less the industrial plant pays for delivered energy. Suppose we wish to determine if there is a difference in the average investment/quad between using electricity and using gas. Our null and alternative hypotheses would be: A) $H _ { 0 } : \left( \mu _ { e } - \mu _ { g } \right) = 0$ vs. $H _ { a } : \left( \mu _ { e } - \mu _ { g } \right) \neq 0$
B) $H _ { 0 } : \left( \mu _ { e } - \mu _ { g } \right) = 0$ vs. $H _ { a } : \left( \mu _ { e } - \mu _ { g } \right) > 0$
C) $H _ { 0 } : \left( \mu _ { e } - \mu _ { g } \right) = 0$ vs. $H _ { a } : \left( \mu _ { e } - \mu _ { g } \right) < 0$
D) $H _ { 0 } : \left( \mu _ { e } - \mu _ { g } \right) = 0$ vs. $H _ { a } : \left( \mu _ { e } - \mu _ { g } \right) = 0$