Which revision best clarifies the relationship of the events described in this sentence?
Jennifer and Carlos were happy to finish their science project, and they had worked on it for more than a month.
O A Jennifer and Carlos were happy to have worked on their science project for more than a month but finished it
B. Jennifer and Carlos were happy to finish their science project, so they had worked on it for more than a month.
OC. When Jennifer and Carlos were happy to finish their science project, they had worked on it for more than a month.
D. Jennifer and Carlos were happy to finish their science project after they had worked on it for more than a month.