In relation to primary radar, what does the term Pulse Recurrence Frequency signify?

Question

Question ATPL - Airline Transport Pilot license - Radio Navigation

QuizVDS · Accepted Answer

The number of pulses transmitted per second.

QuizVDS · Answer

The time between each transmission of pulses.

QuizVDS · Answer

The number of revolutions performed by the radar antenna per minute.

QuizVDS · Answer

Uses pulse technique to determine the radial.

Id 140 - ATPL - In relation to primary radar, what does the term Pulse Recurrence Frequency signify?