The project activities are given in the following table along with the duration and dependency.

$$\begin{array}{|c|c|} \hline \textbf{Activities} & \textbf{Duration (days)} & \textbf{Depends on}\\ \hline \text{P} & 10 & - \\ \hline \text{Q} & 12 & - \\ \hline \text{R} & 5 & \text{P} \\ \hline \text{S} & 10 & \text{Q} \\ \hline \text{T} & 10 & \text{P, Q}\\ \hline \end{array}$$

Which one of the following combinations is correct?

1. Total duration of the project = $22$ days, Critical path is $\text{Q} \rightarrow \text{S}$
2. Total duration of the project = $20$ days, Critical path is $\text{Q} \rightarrow \text{T}$
3. Total duration of the project = $22$ days, Critical path is $\text{P} \rightarrow \text{T}$
4. Total duration of the project = $20$ days, Critical path is $\text{P} \rightarrow \text{R}$