A restaurant manager is creating a trend line for use in estimating his future revenue levels. The manager wants to use the last eight years of his operation’s revenue for his regression analysis, but the data from year number five is missing. What is true in this scenario? 

a. The manager should insert his best estimate of the year five data for the missing data.

b. The manager should insert the data from one year ago for the missing data.

c. The manager should insert the data from eight years ago for the missing data.

d. The manager should insert the average from the seven known years for the missing data.