The table below shows the regression output with sales as the dependent variable and advertising expenditure ($) and time period, t (year) as the independent variables. What is the correct interpretation of the slope coefficient time period? Intercept Advertising exp t Coefficientsandard Errt Stat P-value 31232.5 46332.7 0.67409 0.56972 -0.06504 1.21555 -0.05351 0.96219 18120.3 10091.3 1.79565 0.21439 O the sales is estimated to increase by 18120.3 for a one year increase in the time period. O After controlling for the effect of time period, the sales is estimated to decrease by 0.06 for a dollar increase in the advertising exp. After controlling for the effect of advertising exp, the sales is estimated to increase by 31232.5 for a one year increase in the time period. After controlling for the effect of advertising exp, the sales is estimated to increase by 18120.3 for a one year increase in the time period.