AT 373 K, a gaseous reaction A `rarr` 2B + C is found to be of first order. Starting with pure A, the total pressure at the end of 10 min. was 176 mm and after a long time when A was completely dissociated, it was 270 mm. The pressure of A at the end of 10 minutes was :
A. 94 mm
B. 47 mm
C. 43 mm
D. 90 mm