A. That so many advances have been made in such short time is the most valid argument for retaining the research unit
B. That so many advances have been made in short time is the most valid argument for retaining the research unit
C. That so many advances have been made in so short time is the most valid argument for retaining the research unit
D. That so many advances have been made in so short a time is the most valid argument for retaining the research unit
