500
Given:
If there was lightning, then we did not swim.
If there was lightning, then we did not jog.
Using either one or both of the given statements, which conclusion is valid?
A If we did not swim, the we did not jog.
B If we did not jog, then there was lightning.
C If we did swim, then we did not jog.
D If we did jog, then there was not lightning.
What is D: If we did jog, then there was not lightning.