Ineed this question to be answered right !

The surface area doesn't depend on the unit you use to describe it,
but the number in the description does.

Definition:                                  1 cm  =  10 mm

Square each side:                 (1 cm)²  =  (10 mm)²

                                        (1)² · (cm)²  =  (10)² · (mm)²

                                                1 cm²  =  100 mm²

So if the area is 100 cm² but you want to describe it in mm² instead,
the number will become bigger.

Choice-C says this.