During the past three weeks sales of a brand of medicine have been as follows:

Week

Sales

$1$

$71$

$2$

$70$

$3$

$69$

Using exponential smoothing with a smoothing constant of $\mathrm{.}40,$ ?forecast sales for week $4.($ Note: Round answer to the nearest whole number of sales $)$

Group of answer choices

$72$

$71$

$69$

$70$