Solution:The pumping Lemma for context free languages that for any context - free language L, there exists a constant 'n' (called the pumping length) such that any string S in L, with length at least 'n' can be divded into five pieces u, v, w, x, y satisfying the following conditions.
1. For each i ≥ 0 the string uv w xy is also in L.
2. |vwx| ≥ 1 (i.e. the combined length of v and x is at least 1)
3. |vwx| ≤ n (i.e. the combined length of v and x is at most the pumping length.)
So in this context, the minimum length of 'vx' to gather (i.e. |vwx|) for a language to satisfy the pumping Lemma is 1. So option (b) is correct.