Given the following grammar, select the strings that it accepts.

real - numbersignpart.part|signpart

sign+|-

part digit|digitpart

digit0|1|2|3|4|5|6|7|8|9

i.+32.52

ii.3

iii.-.5

iv.-000.

I know what the write answer is but I don't know how or why it is the right answer. If someone could explain what the right answer and most importantly, how and why it is the right answer, and why the wrong answers are wrong, I would deeply appreciate it.