A regression analysis between sales,y,(in $1,000) and advertising,x,(in $1,000) resulted in the following least squares line: y=80+5.0x

Interpret the estimated slope of the line.

A: As advertising increases by $1,000, sales increases by $5,000.

B: As advertising increases by $1,000, sales increases by $80,000.

C: As advertising increases by $5, sales increases by $80.

D: As advertising increases by $1, sales increases by $5.