The strength of a fully matured concrete sample is 500 kg/cm2. When cured at an average temperature of 20°C in day, 10°C in night, datum temperature T0 is – 11°C. If Plowman constants A is 32 and B is 54, the strength of identical concrete at 7 days will be nearly

• A. 333 kg/cm2
• B. 312 kg/cm2
• C. 272 kg/cm2
• D. 243 kg/cm2