Two identical solid hemispheres each of radius 5cm are first joined along their flat faces to form a sphere. The sphere is then fixed on the top of a right circular cylinder of the same radius 5cm, by joining their flat circular faces. When calculating the total outer surface area of the resulting solid, which of the following areas must be excluded from the calculation?
a) Exactly two circular areas of radius 5cm
b) Exactly one circular area of radius 5cm
c) Exactly three circular areas of radius 5cm
d) No circular area needs to be excluded