Question: How many Grand Slam singles championships were won by the winner of the 1974 Virginia Slims of Newport?
Sentence (from "1974 Virginia Slims of Houston"): The 1974 Virginia Slims of Houston was a women's tennis tournament played on indoor carpet courts at the Net-Set (West Side) Racquet Club in Houston, Texas in the United States that was part of the 1974 Virginia Slims World Championship Series.
Relevant evidence: No