Researchers Are Interested in the Effects of Wind Direction and Season

Multiple Choice

Researchers are interested in the effects of wind direction and season on ozone levels in North America. The ozone levels were recorded at locations, along with the direction of prevailing winds (E, N, S, W) and the season (winter, spring, summer, fall) . A balanced design was carried out such that each combination was observed five times. A partial ANOVA table is provided here:
What is the correct null hypothesis for the test of significance due to direction?

$\begin{array}{l}\begin{array}{lllll}\text { Source } & \text { DF } & \text { SS } & \text { MS } & \text { F } \\\hline \text { Direction } & & 172 & & \\\text { Season } & & 19 & & \\\text { Interaction } & & 48 & & \\\text { Error } & & 519 & & \\\hline\end{array}\\\text { C. Total } \quad \quad \quad \quad \quad 1830\end{array}$

A) H₀: μ_N = μ_S = μ_E = μ_W
B) H₀: μ_Spring = μ_Summer = μ_Fall = μ_Winter
C) H₀: μ_N = μ_S = μ_E = μ_W = μ_Spring = μ_Summer = μ_Fall = μ_Winter
D) H₀: μ_N ≠ μ_S ≠ μ_E ≠ μ_W