Find Sum of the Pair of Complex Numbers $5 - 5 \mathrm { i } , 10 - 11 \mathrm { i }$

Find sum of the pair of complex numbers.
- $5 - 5 \mathrm { i } , 10 - 11 \mathrm { i }$

A) $16 - 15 \mathrm { i }$
B) $15 - 6 i$
C) $15 - 16 i$
D) $15 + 6 \mathrm { i }$