Number systems — Maths STD 9 — Question

On number line, we have $-\infty$ to $\infty$ numbers, consisting $-\infty...-4,-3,-2,-1,0,1,2,3,4...\infty, 1.12,1.14$ and $1.41406532, 3.146201286295...$ etc. That means on number line, there are natural nmbers $(1, 2, 3, 4 ...),$ integers, rational numbers $\frac{1}{2},\frac{1}{3},1.3333,$ irrational numbers $1.4148625385...$
But if we see every number as a complete family, it becomes
Real numbers $($any number which can be represent on Real axes$)$
So, every point on the number line reoresent a unique real number which contains every type.
Hence, option $(a)$ is correct.