Recall the definition of a state variable

A state variable (state function) is a property whose value depends only on the current state of the system, not on the path by which the system reached that state.

Check each given quantity

The quantities given are:

• Internal energy $U$
• Volume $V$
• Heat $q$
• Enthalpy $H$

Now classify them:

(i) Internal energy $U$
Internal energy is a state function.

(ii) Volume $V$
Volume is a state function.

(iii) Heat $q$
Heat is not a state function; it is a path function because it depends on the process.

(iv) Enthalpy $H$
Enthalpy is a state function.

Count the number of state variables

State variables among the given quantities are: $U, \, V, \, H$

Therefore, the total number of state variables is: $3$

Comparison with stored answer

Stored correct answer = $3$
Derived answer = $3$

Hence, they agree.