Term Estimate STE T$-$Ratio Prob$>|$t$|$

Advertising Channel $[$Mail$]-13\mathrm{.}92\mathrm{.}39-5\mathrm{.}81<\mathrm{.}0001$

The above output shows the estimates. What is a correct interpretation of the output.

a The effect of Advertising channel is statistically significant at p$<0\mathrm{.}0001.$

b he parameter estimate for factor A is $-13\mathrm{.}9.$

c All are correct.

d The response is $27\mathrm{.}8$ lower when using MAIL as Advertising Channel than for the other level of Advertising Channel.