For a ten-month period, the total monthly sales of new cars within the country of Calistan remained constant. During this period the monthly sales of new cars manufactured by Marvel Automobile Company doubled, and its share of the new car market within Calistan increased correspondingly. At the end of this period, emission standards were imposed on new cars sold within Calistan. During the three months following this imposition, Marvel Automobile Company’s share of the Calistan market declined substantially even though its monthly sales within Calistan remained constant at the level reached in the last month of the ten-month period.

If the statements above are true, which one of the following CANNOT be true?
(A) The total monthly sales within Calistan of new cars by companies other than Marvel Automobile Company decreased over the three months following the imposition of the emission standards.
(B) Over the three months before the imposition of the emission standards, the combined market share of companies other than Marvel Automobile Company selling new cars in Calistan decreased.
(C) If the emission standards had not been imposed, Marvel Automobile Company would have lost an even larger share of the number of new cars sold in Calistan than, in fact, it did.
(D) A decrease in the total monthly sales of new cars within Calistan will occur if
the emission standards remain in effect.
(E) Since the imposition of the emission standards, Marvel Automobile Company’s average profit on each new car sold within Calistan has increased.

I was lost in the premise and then in the answer choices.

can someone suggest a better and quicker way of approaching such questions?