Express the Sum Using Summation Notation $$a + a r + a r ^ { 2 } + \ldots + a r ^ { 15 }$$

Multiple Choice

Express the sum using summation notation. Use a lower limit of summation, not necessarily 1, and k for the index of summation.
- $$a + a r + a r ^ { 2 } + \ldots + a r ^ { 15 }$$

A) $\sum _ { \mathrm { k } = 1 } ^ { 15 } a r ^ { \mathrm { k } }$
B) $\sum _ { k = 0 } ^ { 15 } a r ^ { k }$
C) $\sum _ { \mathrm { k } = 1 } ^ { 16 } a \mathrm { r } ^ { \mathrm { k } }$
D) $\sum _ { k = 0 } ^ { 15 } ( a r ) ^ { k }$