It had been over a period of six months that the turbine produced up to 211 gallons of water per day.
What is the most effective way to revise this sentence?
a. It had been over a period of six months, the turbine produced up to 211 gallons of water per day.
b. Because it had been over a period of six months, the turbine produced up to 211 gallons of water per day.
c. Over a period of six months, the turbine produced up to 211 gallons of water per day.
d. The turbine produced up to 211 gallons of water per day, this was over a period of six months.