In the following expressions. - represents negation of a variable. For example. -x stands for "NOT x"). + represents logical OR. and juxtaposition represents logical AND (e.g.. (x + y)(y + z) represents (x OR y) AND (y OR z). Identify the expression that is satisfiable. from the list below. a) (-z + y)(-z + -y)(y + x)(z) b) (-z + y)(-z + -y)(z + y)(z + -y) c) (z + -y)(-y + x)(-z)(-x + z) d) (z + -y)(y-x)(-x-z)(-z)