Task: Class Definition Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes 'spreading rate'?

A. The character and amount of atmospheric pressure change during a specified period of time, often a three-hour period preceding an observation.
B. The rate of recurrence of any periodic phenomenon, often associated with waves of all kinds. Without qualification the concept often means temporal the concept, the rate of recurrence of a time-varying function, but could mean spatial the concept, the rate of recurrence of a space-varying function. Spatial the concept is the reciprocal of the repeat distance (sometimes the wavelength). The dimensions of (temporal) the concept are inverse time. A common unit for the concept is cycle per second, formerly abbreviated cps, but superseded by hertz, abbreviated as Hz.
C. The the concept is a measure of how fast plate divergence is occurring. [Wikipedia]
D. 1. According to U.S. weather observing practice, a fog that hides less than 0.6 of the sky and does not extend to the base of any clouds that may lie above it. As an obstruction to vision in an aviation weather observation, the concept is encoded GF. 2. See radiation fog.

Answer: The the concept is a measure of how fast plate divergence is occurring. [Wikipedia]