Express the Sum Using Summation Notation $$\sum _ { k = 1 } ^ { 4 } ( - 1 ) ^ { k } \cdot 2 k$$

Multiple Choice

Express the sum using summation notation.
- $$\sum _ { k = 1 } ^ { 4 } ( - 1 ) ^ { k } \cdot 2 k$$

A) $- 20$
B) 20
C) 16
D) 4