**A.**

1**B.**

2**C.**

3**D.**

4

##### Correct Answer: Option B

##### Explanation

(begin{array}{c|c} Scores & 1 & 2 & 3 & 4 & 5 & 6 \ hline text{No. of students} & 1 & 4 & 5 & 6 & x & 2end{array})

Average = 3.5

3.5 = (frac{(1 times 1) + (2 times 4) + (3 times 5) + (4 times 6) + 5x + (6 times 2)}{1 + 4 + 5 + 6 + x + 2})

(frac{3.5}{1}) = (frac{1 + 8 + 15 + 24 + 5x + 12}{18 + x})

(frac{3.5}{1}) = (frac{60 + 5x}{18 + x})

60 + 5x = 3.5(18 (div) x)

60 + 5x = = 63 + 1.5x

5x – 1.5x = 63 – 60

1.5x = 3

x = (frac{3}{1.5})

(frac{30}{15}) = 2