For most places on earth, what is the time difference between two low tides? a. about 12 hours b. about 24 hours c. once a month d. once every three months

For most places on earth,  the time difference between two low tides is  the  about 12 hours because there are two tides a day
 so the correct option i conclude is A 
hope it helps

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.