Graduate Pharmacy Aptitude Test (GPAT) 2012 Solved Paper

There are some statements related to the protein binding of drugs as given below:
[P] : Protein binding decreases the free drug concentration in the system.
[Q]: Protein binding to plasma albumin is an irreversible process.
[R] : Drugs with a low lipophilicity have a high degree of protein binding.
[S] : Protein binding of one drug can be affected by the presence of other drug.
Choose the correct combination of statements.