Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Angela Martinez, an energy sector analyst at an investment bank, is concerned about the future level of oil prices and how it might affect portfolio values. She is considering whether to recommend a hedge for the bank portfolio's exposure to changes in oil prices. Martinez examines West Texas Intermediate (WTI) monthly crude oil price data, expressed in US dollars per barrel, for the 181-month period from August 2000 through August 2015. The end-of-month WTI oil price was $51.16 in July 2015 and $42.86 in August 2015 (Month 181).After reviewing the time-series data, Martinez determines that the mean and variance of the time series of oil prices are not constant over time. She then runs the following four regressions using the WTI time-series data.Linear trend model: Oil pricet = b0 + b1t + etLog-linear trend model: In Oil pricet = b0 + b1t + etAR(1) model: Oil pricet = b0 + b1Oil pricet-1 + etAR(2) model: Oil pricet = b0 + b1Oil pricet-1 + b2Oil pricet-2 + etExhibit 1 presents selected data from all four regressions, and Exhibit 2 presents selected autocorrelation data from the AR(1) models.
Based on the regression output in Exhibit 1, there is evidence of positive serial correlation in the errors in:
Option A:the linear trend model but not the log-linear trend model.
Option B:both the linear trend model and the log-linear trend model.
Option C:neither the linear trend model nor the log-linear trend model.

Answer: B