Sasha and Mona practiced swimming every day. They increased the number of minutes of swimming every week as described below: Sasha: Practiced swimming for 10 minutes every day in the first week, 20 minutes in the second week, 40 minutes in the third week, and 80 minutes in the fourth week. Mona: Practiced swimming for 10 minutes every day in the first week, 20 minutes in the second week, 30 minutes in the third week, and 40 minutes in the fourth week. Which statement best describes the methods used by Sasha and Mona to increase the time they practiced swimming?
Mona's method is linear because the number of minutes increased by an equal factor every week.
Sasha's method is exponential because it increases by an equal number every week.
Mona's method is exponential because it increases by a fixed factor, and Sasha's method is linear because it increases by a fixed number.
Sasha's method is exponential because it increases by a fixed factor, and Mona's method is linear because it increases by a fixed number.

As per given statements we see the time of Sasha practice it increases by a fixed factor of '2' or we can say Sasha's time is multiplied by '2' every week.

When we see the time of Mona's practice, it increases by 10 mins every week. hence there is a addition of a fixed number '10'.

so option D is correct which says Sasha's method is exponential because it increases by a fixed factor, and Mona's method is linear because it increases by a fixed number.