Read the paragraph carefully and answer the questions given below.
paragraph : While giving IUPAC names of the organic compounds having more than one functional group the functional group with highest priority is considered as principal functional group and other functional groups are considered as substituted group. Carbon chain is given numbers in such away that principal functional group gets least number.
IUPAC name of following compound is ....... .
(A) Methyl 4-cyano-3-methoxy pentanoate
(B) 4-methoxy-carbonyl-1-methoxy butanenitrile
(C) Methyl-4-cyano-3-methoxy butanoate
(D) 4-carbmethoxy-2-methoxy butanenitrile