Challenge question I dont get at all

Question

So I got the last question on a challenge correct by luck and dont understand what any of it is doing at all.
<input type="number" name="values" min="0" max="30" step="7" value="0">

Options:
a. 14, 0, 28, 7, 17
b. 7, 23, 14, 0, 28
c. 30, 0, 7, 28, 14
d. 0, 21, 7, 28, 14
(correct answer is d but why?)

Answer 1

In the input tag for the question, the different attributes are setting the value to be entered to be restricted to any numbers between 0 and 30 and a multiple of 7 (in step="7"). d would be the correct answer as all of the numbers in that list are multiples of 7 (in order it would be 7*0, 7*3, 7*1, 7*4, and 7*2) and are all in the range specified by the min and max attributes.