After BCG vaccination, when is the local skin response (scar formation) usually seen and considered as evidence of effective vaccination?

Correct option is B

BCG vaccination produces a local nodule → ulcer → scar. The typical scar develops in 4–6 weeks, considered as evidence of successful vaccination.
Explanation of options: (a) ✘ At 1–2 weeks, only small induration is seen, not scar. (b) ✔ Correct; scar forms around 4–6 weeks. (c) ✘ At 8–10 weeks, scar may persist, but response is expected earlier. (d) ✘ 12–16 weeks is too late, delayed healing is abnormal.