A chemical reaction will occur spontaneously at constant pressure and temperature, if the free energy is

Answer: Option C

Since for an spontaneous process $$TdS>dU+PdV$$
For, constant temperature and constant pressure process the above equation can be written as
$$\begin{array}{rl}& d\left(TS-U\right)>PdV\\ & \Rightarrow d\left(-A\right)>PdV\\ & \Rightarrow {\left(dG\right)}_{T,P}<0\end{array}$$
For spontaneous process.