K-map (rows cd, columns ab). The 1s are at minterms 0 (a̅b̅c̅d̅), 2 (a̅b̅cd̅), 8 (ab̅c̅d̅) and 9 (ab̅c̅d). The don't cares are 1, 4, 10 and 12.

• Group {0, 2, 8, 10} (the four corners, using don't care 10) gives \(\bar{b}\bar{d}\).
• Group {0, 1, 8, 9} (using don't care 1) gives \(\bar{b}\bar{c}\), which covers minterm 9.

Minimal SOP = \(\bar{b}\bar{d} + \bar{b}\bar{c}\)

Answer: (B)