A 25 -kg child sits on one side of a teeter-totter, at a distance of \(2
\mathrm{~m}\) from the pivot point. A mass \(m\) is placed at a distance \(d\) on
the other side of the pivot, in an effort to balance the teeter-totter. Which
of the following combinations of mass and distance (A, B, C, or D) balances
the teeter-totter? (Assume that the teeter-totter itself pivots at the center
and produces zero torque.)
$$
\begin{array}{|l|l|l|l|l|}
\hline & \text { A } & \text { B } & \text { C } & \text { D } \\
\hline \text { Mass, } \boldsymbol{m} & 10 \mathrm{~kg} & 50 \mathrm{~kg} & 40
\mathrm{~kg} & 20 \mathrm{~kg} \\
\hline \text { Distance, } \boldsymbol{d} & 2 \mathrm{~m} & 1 \mathrm{~m} &
1.5 \mathrm{~m} & 2.5 \mathrm{~m} \\
\hline
\end{array}
$$