In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as 'a' for Yes or 'b' for No.

Question: Which of the two car models that GM used to counter the Plymouth Barracuda in 1967 sold the most units? Passage:The Mustang's success left General Motors unprepared. Chrysler introduced the Plymouth Barracuda a few weeks before the Mustang, and although it was later redesigned as a distinct "pony car", it was initially a modified Plymouth Valiant. However, the "fish car" did not enjoy as strong a market demand as Ford's "pony". General Motors executives thought the rear-engined Chevrolet Corvair Monza would compete against the Mustang, but it also sold poorly by comparison. The Monza performed well, but lacked a V8 engine and its reputation was tarnished by Ralph Nader in his book Unsafe At Any Speed. It took GM until the 1967 model year to counter with the Chevrolet Camaro and Pontiac Firebird. Lincoln-Mercury joined the competition in 1966 with the Mercury Cougar, an "upmarket Mustang" and subsequent Motor Trend Car of the Year. In 1967, American Motors (AMC) introduced the Javelin, an image changing "standout" four-place pony car. In 1969, the Dodge Challenger, a version of the Plymouth Barracuda platform, was last to join the pony car race. This genre of small, sporty automobiles is often referred to as the "pony car" because of the Ford Mustang that established this market segment.
a