What FIS document is this? We use the PPA VS in AA format, and it reads very differently, (and IMHO is much clearer). Ours doesn't have quite the same option as yours, and the closest choice is this - underlining is my emphasis:
_____(not to exceed 12) consecutive month period from the Eligible Employee's employment commencement date and during which at least ______(not to exceed 1,000) Hours of Service are completed. If an Employee does not complete the stated hours of Service during the specified time period, the Employee is subject to the 1 year of service requirement in i above.
I'm honestly not sure how I'd interpret yours, and I would probably ask FIS to clarify. Our document (and I had this confirmed by FIS) would be that if you don't work the requisite number of hours in the initial 3 month period ONLY, then you revert to the "Year of Service" standard, and there are no subsequent 3 month measurement periods - even in the first year.