Correct Option: B

Here , The average age of 9 students and teacher = 16 years
Total age of 9 students and teacher = 16 × 10
The average age of the first four students = 19 years
Total age of the first four students = 19 × 4
And the average age of the last five students = 10 years
Total age of the last five students = 5 × 10
∴ Teacher’s age = 16 × 10 – 19 × 4 – 5 × 10
Teacher’s age = 160 – 76 – 50 = 34 years