The spread of a dataset tells us how much the elements are distant from each other.
So, we look at the distance between the minimum and the maximum values for each dataset:
[tex]\begin{array}{c|c|c|c}\text{Dataset}&\text{Min}&\text{Max}&\text{Difference}\\A&12&55&43\\B&12&56&44\end{array}[/tex]
So, set B has a greater spread.