A Researcher Wanted to Determine If Using an Octane Booster

A researcher wanted to determine if using an octane booster would increase gasoline mileage. A random
sample of seven cars was selected; the cars were driven for two weeks without the booster and two weeks
with the booster.
$$\begin{array} { | l | l | } \hline \text { Miles / Gal Without } & \text { Miles / Gal With } \\\hline 21.2 & 23.8 \\\hline 25.4 & 25.6 \\\hline 20.9 & 22.4 \\\hline 27.6 & 28.3 \\\hline 22.8 & 24.5 \\\hline 27.3 & 28.8 \\\hline 23.4 & 25.2 \\\hline\end{array}$$
-State the alternative hypothesis.

A) $H _ { 1 } : \mu _ { D } = 0$
B) $H _ { 1 } : \mu _ { D } > 0$
C) $H _ { 1 } , \mu _ { D } < 0$
D) $H _ { 1 } = \mu _ { D } = 0$