The values of a and b from the table are:

x	y
3	18
5	a
b	90
8	48

1. a = 30 and b = 270

2. a = 30 and b = 15

3. a = 45 and b = 15

4. a = 30 and b = 540

$\dfrac{3}{18} = \dfrac{1}{6}$

$\dfrac{8}{48} = \dfrac{1}{6}$

So, we can say that x and y vary directly

$\therefore \dfrac{3}{18} = \dfrac{5}{a} = \dfrac{b}{90} = \dfrac{8}{48}\\[1em] \Rightarrow \dfrac{3}{18} = \dfrac{5}{a} \text{ and } \dfrac{3}{18} = \dfrac{b}{90}\\[1em] \Rightarrow a = \dfrac{5 \times 18}{5} \text{ and } b = \dfrac{3 \times 90}{18}\\[1em] \Rightarrow a = \dfrac{90}{3} \text{ and } b = \dfrac{270}{18}\\[1em] \Rightarrow a = 30 \text{ and } b = 15$

Hence, option 2 is the correct option.