Given $f(w, x, y, z) = \Sigma_m(0,1, 2, 3, 7, 8, 10) + \Sigma_d(5, 6, 11, 15)$; where $d$ represents the 'don't-care' condition in Karnaugh maps. Which of the following is a minimum product-of-sums (POS) form of $f(w, x, y, z)$?
- $f=(\bar{w}+\bar{z}) (\bar{x}+z)$
- $f=(\bar{w}+z) (x+z)$
- $f=(w+z) (\bar{x}+z)$
- $f=(w+\bar{z}) (\bar{x}+z)$