A. There is a staff of 400 in this research institute, of whom 20 are senior research scientists. There are 7 laboratories, 1 small library and related factory where there are 120 workers

B. The research institute has a staff of 400, of whom 20 are senior researchers. It has 7 laboratories,1 small library and 1 related factory that has 120 workers

C. The research institute staffed with personnel of 400, of whom 20 are senior research fellows, has 7 laboratories, 1 small library and 1 related factory with 120 workers

D. There is 400 staff in this research institute, of whom 20 are senior research scientists. There are 7 laboratories, 1 small library and related factory where there are 120 workers