The given figure shows lac operon model and its functioning. Select the option which correctly labels A, B, X, Y and Z marked in the figure and also identify the label which is primarily responsible for the hydrolysis of the disaccharide, lactose, into galactose & glucose.

In the given figure of lac operon model (proposed by Jacob and Monad), the labels A, B, X, Y and Z are respectively repressor, inducer, b- galactosidase (z), permease (y), transacetylase (a). z, y and a are three structural genes which produces three enzymes for the degradation of lactose to glucose and galactose. Label X (b- galactosidase) is primarily responsible for the hydrolysis of disaccharide lactose into galactose and glucose.