Given f(w, x, y, z) = ∑m (0, 1, 2, 3, 7, 8, 10) + ∑d (5, 6, 11, 15), where d represents the don’t-care condition in Karnaugh maps. Which of the following is a minimum product-of-sums (POS) form of f(w, x, y, z)?

• A. f = (w̅ + z̅ )(x̅ + z)
• B. f = (w̅ + z)(x + z)
• C. f = (w + z)(x̅ + z)
• D. f = (w + z̅ )(x̅ + z)