The correct option is (B): 5m
Given that: Garden's Area= \(100\space m^2\)
let length=L and width= B
⇒ \(L\times B=100\space m^2\)
from Option A: \(B=10\)(It will become square)
Option C: \(B=50\space L=2\)(Since he only fences three sides, either 2L + B = 30 or L + 2B = 30. However, neither of these equations meets the required condition.
Option D: \(B=100 \space cm\) (cannot be alone with 100)
So the correct answer is option B. Width of garden =5 m