You suspect that, except for noise, a time series Y follows an upward exponential trend. Assuming you are correct, which of the following is true?

a. If you apply the LN function to each of the observations, the resulting series will essentially be a straight upward-sloping line.

b. If you apply the EXP function to each of the observations, the resulting series will essentially be a flat line.

c. If you apply the EXP function to each of the observations, the resulting series will essentially be a straight upward-sloping line.

d. If you apply the LN function to each of the observations, the resulting series will essentially be a flat line.