From the given speed-density curve, we can determine the maximum flow by finding the point where the product of speed \( u \) and density \( k \) is maximized. This corresponds to the point where the slope of the curve is zero.
The formula for the maximum flow \( q_{{max}} \) is given by:
\[
q_{{max}} = \frac{k_j}{2} \times v_f \times \left( \frac{k_{{max}}}{2} \right),
\]
where:
- \( k_j = 100 \, {veh/km} \) (jam density),
- \( v_f = 100 \, {km/h} \) (free flow speed),
- \( k_{{max}} = 100 \, {veh/km} \) (maximum density).
Substituting these values into the formula:
\[
q_{{max}} = \frac{100}{2} \times 100 \times \left( \frac{100}{2} \right) = 2500 \, {veh/hr}.
\]
Thus, the maximum flow on this road is 2500 vehicles/hour, which corresponds to option (A).