Here Is Some Output from a Regression Analysis $\text { Model Summary }$

Here is some output from a regression analysis:
$\text { Model Summary }$
$\begin{array}{|l|r|r|}\hline & R & R \text { Square } \\\hline & .436^{a} & .190 \\\hline\end{array}$
a. Predictors: (Constant), Age When First Married,
Number of Brothers and Sisters, Age of Respondent $\begin{array}{|l|r|r|r|}\hline &\text { Standardized } \\&\text { Coefficients }\\Model&\text { Beta } & t& {\text { Sig. }} \\\hline 1 \quad \text{Number of Brothers and Sisters}&.152 & 5.787 & .000 \\ ~\quad\text{Age of Respondent}&.299 & 11.338 & .000 \\~ \quad\text{Age When First Married}&-.283 & -10.802 & .000 \\\hline\end{array}$
-Which of the three independent variables is the best predictor? How can you tell?