Recall the definitions

• Heat capacity / thermal capacity of a body is the amount of heat required to raise the temperature of the entire body by $1\,\text{K}$.
• Specific heat (or specific heat capacity) is the amount of heat required to raise the temperature of unit mass of a substance by $1\,\text{K}$.
• Water equivalent is the mass of water that would absorb/release the same amount of heat as the body for the same temperature change.

Interpret the question

The question says:

The heat required to raise the temperature of body by $1\,\text{K}$ is called ...

Since it refers to the whole body, not unit mass, the correct term is thermal capacity.

Evaluate the options

• A: specific heat → Incorrect, because this is for unit mass.
• B: thermal capacity → Correct.
• C: water equivalent → Incorrect.
• D: none of these → Incorrect.

Final answer

$\boxed{\text{B: thermal capacity}}$