For the parallelogram OPQR shown in the sketch, \[ OP = a t + b j\] and \[ OR = c t + d j .\] The area of the parallelogram is

For the parallelogram OPQR shown in the sketch, $$\overline{\mathrm{OP}}=\mathrm{a}\hat{\mathrm{t}}+\mathrm{b}\hat{\mathrm{j}}$$   and $$\overline{\mathrm{OR}}=\mathrm{c}\hat{\mathrm{t}}+\mathrm{d}\hat{\mathrm{j}}.$$   The area of the parallelogram is

Answer: Option A