What is the periodicity of Halley's comet?

75-76 years

The correct answer is option 4. 75-76 years.

Halley's Comet has a periodicity of 75-76 years.

Halley's Comet is one of the most famous periodic comets, visible from Earth approximately every 75 to 76 years. It last appeared in the inner solar system in 1986 and is expected to return around the year 2061.