Summation notation Sigma NEED HELP ASAP!

Question

Express the sum using sigma notation:

 (2 points)

Answer Choices:

Answer 1

Solve by trial and error. If we explore option D:

For k = 1: numerator = k = 1, denominator = k² + 1 = 1² + 1 = 2

For k = 2: numerator = k = 2, denominator = k² + 1 = 2² + 1 = 5

For k = 3: numerator = k = 3, denominator = k² + 1 = 3² + 1 = 10

For k = 4: numerator = k = 4, denominator = k² + 1 = 4² + 1 = 17

For k = 5: numerator = k = 5, denominator = k² + 1 = 5² + 1 = 26

This will create the correct series, so your answer is D