Leonardo offered his services to the duke of milan first as and only secondly as an artist

I believe the answer is: Millitary engineer

The main reason why duke of Milan employed Leonardo is that the duke want him to design a military weapon that the government of Milan can use to improve their defense artillery. As an artist, the duke ask Leonardo to paint the design on the largest churches in his territory.

hello again!

a is your answer!

true because they can bargain