Explanation:

- The ratio of sales is given as 5:4:8:3 for Monday, Tuesday, Wednesday, and Thursday. The sales on Wednesday are 160 phones.

- Since the ratio for Wednesday is 8, let the common multiplier be x. Therefore, 8x = 160.

- Solving for x, we get x = 160/8 = 20.

- Monday’s sales will be 5 * 20 = 100 phones.

- Sales on Friday are 20% more than Monday's. Thus, sales for Friday = 100 + (20/100) * 100 = 100 + 20 = 120 phones.

- Option 4: 120 phones is the correct choice.