Assertion (A) : If 5 parallel lines intersect 4 parallel lines, then the number of parallelograms formed is 80 

Reason (R) : The number of parallelograms formed when a set of m parallel lines are intersecting another set of n parallel lines is ${ }^m{C}_2{\times }^n{C}_2$

The correct answer is  

$\mathrm{A} \mathrm{set} \mathrm{of} 5 \mathrm{parallel} \mathrm{lines} \mathrm{intersect} \mathrm{another} \mathrm{set} \mathrm{of} 4 \mathrm{parallel} \mathrm{lines}$

$\begin{array}{rcl} & \Rightarrow & \mathrm{Number} \mathrm{of} \mathrm{parallelograms} \mathrm{formed} = 5{\mathrm{C}}_2\times 4{\mathrm{C}}_2\\ & =& 10\times 6\\ & =& 60\end{array}$

$\begin{array}{rcl} & & \therefore \mathrm{A} \mathrm{is} \mathrm{false}, \mathrm{R} \mathrm{is} \mathrm{true}\end{array}$