Answer:
d. both b and c
Step-by-step explanation:
Standard enthalpy is typically measured at standard atmospheric pressure and standard state conditions, which means a pressure of 1 atmosphere and at a specified temperature that may vary depending on the context. However, it is common to use room temperature (around 25 degrees Celsius or 298 Kelvin) as the standard temperature for measuring enthalpy. Therefore, the standard enthalpy is measured at both standard atmospheric pressure and standard state conditions, as well as at room temperature and 1 atmosphere.