To solve this question we must know the difference between discrete and continuous variables.
Discrete variables are the ones we count using the fingers:
n = 0, 1, 2, 3, 4,... and so on
We can also use negative numbers to do so:
n = ...-4, -3, -2, -1, 0
Continuous variables can't be count using our fingers. For instance, we can take a small interval, say, from 0 to 1 and give some examples of numbers that lie in that interval:
interval = 0 to 1
The number 1/2 = 0.5 lies in the interval
The number 1/3 = 0.333 lies in the interval too
The number 0.9998 lies in the interval too
And so on.
What do I mean with that? There are inifity numbers that we can't count, all of them that lies on the interval.
Let's go to the problem:
a)
The number of hits on a website can be count: 1, 2, 3,...., 1,458, ..., 1,506,897 and so on. So it is a discrete variable.
Answer: option D.
b)
The ammount of rain can be meaured by the height of the water that has poured down on that day. Let's say we measure using milimeters (mm). Then the ammount of water could be 125 mm, or even 189.6 mm. There is a infinite set of numbers that could be used. So we have a continuous variable.
Answer: option B