If \( A \) and \( B \) are two events such that \( P(A) = 0.7 \), \( P(B) = 0.4 \) and \( P(A \cap \overline{B}) = 0.5 \), where \( \overline{B} \) denotes the complement of \( B \), then \( P\big(B \mid (A \cup \overline{B})\big) \) is equal to:
\( \dfrac{1}{6} \)
\( \dfrac{1}{3} \)
\( \dfrac{1}{2} \)
\( \dfrac{1}{4} \)
