The answer choice which represents the series in sigma notation is; Choice D.
Representing series in Sigma notation
A series can be represented in a compact form, called summation or sigma notation. The Greek capital letter, ∑ , is used to represent the sum.
On this note, the representation of the series as described in the task content is best described by; Choice D, with lower and higher summation limits 1 and 7 respectively.
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