Who was the only woman to achieve a top-six finish in a Formula One Grand Prix?
Correct!
Lella Lombardi was classified 6th, two laps down, in the 1975 Spanish Grand Prix at the Montjuic street circuit in Barcelona, hosting F1 for the final time. The race was beset with safety issues, (reigning World Champion
Emerson Fittipaldi did not even attempt to quaify), and the race was stopped after 29 laps following numerous accidents, one of which resulted in the death of five spectators.
Jochen Maas won the race, his only F1 victory, but since the race was shortened, he only earned 4½ championship points, and Lombardi's sixth place was worth half a point.
Later that year, fifth-place finisher,
Vittorio, ("The Monza Gorilla"), Brambilla, Lombardi's team mate at March, would also win the only race of his F1 career, also shortened to 29 laps, at the Austrian Grand Prix. Brambilla crashed his car following the red flag that ended the race, (extreme wet conditions), when he took both hands off his steering wheel to give victory waves to the crowd.