True about following is?

Ans. B. 121-degree C at for 15 minHeat sterilization (Autoclave)-:a. A widely-used method for heat sterilization is the autoclave.b. Autoclaves commonly use steam heated to 121 degC or 134 degC.c. To achieve sterility, a holding time of at least 15 minutes at 121 degC or 3 minutes at 134 degC required.d. Additional sterilizing time is usually required for liquids and instruments packed in layers of cloth, as they may take longer to reach the required temperature.e. After sterilization, autoclaved liquids must be cooled slowly to avoid boiling over when the pressure is released.