The area of the regular pentagon:

where s=6m, and a=3*tg 54°= 3*1.37=4.13 m
Explanation: 54° is a half of the inner angle of the pentagon. The interior angles of a pentagon add up to 540°. Each angle is 108°.
Finally: A=

=61.93 m².
Answer:
C) 61.9 m²