The correct answer is: A. Ratio-to-moving average method.
The ratio-to-moving average method is the most widely used method of measuring seasonal variations. It is a simple and effective way to identify and measure seasonal patterns in data. The method involves calculating the ratio of each data point to the corresponding moving average. The moving average is a smoothed version of the data that helps to reduce the effects of random fluctuations. The ratio of each data point to the moving average is then used to measure the seasonal variation for that data point.
The ratio-to-moving average method can be used to identify seasonal patterns in both time series and cross-sectional data. It is also relatively easy to implement and interpret. However, it is important to note that the ratio-to-moving average method does not take into account any other factors that may be affecting the data, such as trend or cyclical effects.
The other options are:
B. Ratio-to-trend method: This method involves calculating the ratio of each data point to the corresponding trend line. The trend line is a line that represents the long-term trend in the data. The ratio of each data point to the trend line is then used to measure the seasonal variation for that data point.
C. Link relative method: This method involves calculating the link relative for each data point. The link relative is a measure of the relative change in the data from one period to the next. The link relative for each data point is then used to measure the seasonal variation for that data point.
D. None of these: This option is incorrect. The ratio-to-moving average method is the most widely used method of measuring seasonal variations.