Answer:
[tex]\large\boxed{C)\ 5cm}[/tex]
Step-by-step explanation:
[tex]P=2(l+w)\\\\\text{Put}\ l=2cm\ \text{and}\ w=\dfrac{1}{2}cm\ \text{to the formula of the perimeter:}\\\\P=2\left(2+\dfrac{1}{2}\right)=(2)(2)+(2)\left(\dfrac{1}{2}\right)=4+1=5\ cm[/tex]