Suppose We Omit X₂ from the Following in a Bivariate $\beta$

Multiple Choice

Suppose we omit X₂ from the following in a bivariate model
Y_i = $\beta$ ₀ + $\beta$ ₁X_1i + $\varepsilon$ _i
And suppose X₂ is negatively related to X₁ and $\beta$ ₂ is positive, while $\beta$ ₁ is positive. What is the likely effect of omitting X₂ on our estimate of $\beta$ ₁?

A) No effect; $\beta$ ₁hat will be unbiased.
B) $\beta$ ₁hat will be more positive than it should be.
C) $\beta$ ₁hat will be less positive than it should be.
D) $\beta$ ₁hat will equal zero.