Which of the Following Linear Combinations of Population Means Is $\mu$

Multiple Choice

Which of the following linear combinations of population means is a legitimate contrast?

A) $\mu$ ₁- $\mu$ ₂/2+ $\mu$ ₃/2
B) ( $\mu$ ₁+ $\mu$ ₂) /2+ $\mu$ ₃
C) ( $\mu$ ₁+ $\mu$ ₂) /2- $\mu$ ₃
D) $\mu$ ₁- $\mu$ ₂- $\mu$ ₃