The average salary of employees in a factory is Rs. 2200. All employees are divided in two grades A and B having an average of Rs. 2450 and Rs. 1950 respectively. If grade A has 10 employees then how many employees have grade B?

1. A Option A: 12
2. B Option B: 16
3. C Option C: 20
4. D Option D: 24
5. E Option E: none

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