Which of the Following States the Objective of Time Series

Which of the following states the objective of time series analysis?

A) To study the variation of time with respect to increase in the variable value
B) To analyze the time-dependent environmental factors that affected variable values in the past
C) To use present variable values to study what should have been the ideal past values
D) To uncover a pattern in the time series and then extrapolate the pattern into the future