281 feet (85 meters)
196 feet (60 meters)
98 feet (30 meters)
842 feet (256 meters)
 
Correct Answer: 281 feet (85 meters)

A little background…

The typical C60 cassette delivered 30 minutes of playback per side at the standard speed using 281.25 feet (85.73 meters) of tape measuring 1/8in (3.81mm) wide and 16µm thick (0.0006in or 0.0159mm). Some manufacturers produced C60s containing more tape, such as Maxwell's cassettes with 295 feet/90 meters of tape.

C90 cassettes carried thinner tape measuring 10 or 11µm and could thus hold more (~426 feet or ~130 meters). Up to C180 cassettes have been developed but the tape required is considered too thin and fragile for most applications due to print through echo. Of note, C74 cassettes were produced specifically for recording a standard length CD.