Convert the Units $870 \mathrm {~mm} ^ { 2 } = ......\quad \mathrm { cm } ^ { 2 }$

Multiple Choice

Convert the units.
- $870 \mathrm {~mm} ^ { 2 } = ......\quad \mathrm { cm } ^ { 2 }$

A) $8.7$
B) $0.87$
C) 870
D) 8700