The Boolean expression \displaystyle\overline{{{\left({a}+\overline{{b}}+{c}+\overline{{d}}\right)}+{\left({b}+\overline{{c}}\right)}}} simplifies to

(a) \displaystyle{1}

(b) \displaystyle\overline{{{a}.{b}}}

(c) \displaystyle{a}.{b}

(d) \displaystyle{0}