a company which is making 200 mobile phones each week will increase its production. The number of mobile phones will increase by 25 each week from 200 in week 1 to 225 in week 2 to 250 in week 3 and so on until it will produce 850 mobile phones. In how many weeks will it produce 850 mobile phones?

a.27
b.21
c.26
d.28​