Agarose gel electrophoresis

I just don't get this question at all! Help me please

If restriction endonuclease digests of a plasmid give the following fragment sizes when analysed by agarose gel electrophoresis

Sal I alone= 4.6 kb
Pst I alone= 2.4 kb, 1.6 kb, 0.6 kb
Sal I + Pst I= 2.4 kb, 1.0 kb, 0.6 kb

which of the statements below is false?

There is probably a single Sal I site in the plasmid
The 0.6 kb band from the double digest probably contains two different fragments
There are probably two Pst I sites in the plasmid
The size of the plasmid is approx. 4.6 kb
The Sal I site must lie within the 1.6 kb Pst I fragment

Help would be greatly appreciated!!