Area of shapes III

This task is about working out the area of shapes.
a)

What is the area of the cross?
(A) 16 cm2
(B) 20 cm2
(C) 24 cm2
(D) 36 cm2.
 
b)

What is the area of the octagon?
(A) 10 cm2
(B) 12 cm2
(C) 14 cm2
(D) 16 cm2.
 
c)

What is the area of the star?
(A) 8 cm2
(B) 12 cm2
(C) 16 cm2
(D) 20 cm2.