Final answer:
The 'Two-period moving average' is not an Excel trendline type. In Excel, users can set a moving average, but it is not specifically categorized by periods like 'two-period' in the trendline options.
Step-by-step explanation:
The question asks which of the following is NOT an Excel trendline type. The available trendline types in Excel are linear, exponential, logarithmic, polynomial (which includes quadratic), power, and moving average. Among the options provided: (1) Quadratic, (2) Linear, (3) Exponential, and (4) Two-period moving average, the one that is not an Excel trendline type is a Two-period moving average.
Excel does allow for moving average trendlines, but they are not specified by the number of periods in the same way that this option suggests. Instead, the user can choose the number of periods over which to calculate the moving average in Excel's trendline options.