A DNA Fragment Produced by the Restriction Enzyme SalI Is

A DNA fragment produced by the restriction enzyme SalI is isolated from a digestion of mouse DNA.You cloned the fragment by first ligating it into a unique Sal I site found in a 3.5 kb cosmid.The ligation into the SalI site regenerates a SalI cut site at each end of the cloned fragment.You decide to determine the restriction map of this fragment.You digest the fragment with different restriction enzymes (below).
Note: The cosmid used in this strategy does not have EcoRI or HindIII sites (but the cloned fragment apparently does).
$\begin{array}{|l|l|}\hline\text { Restriction enzyme } & \text { Fragments produced } \\\hline \text { SalI } & 20 \mathrm{~kb}, 3.5 \mathrm{~kb} \\\hline \text { SalI }+ \text { EcoRI } & 7 \mathrm{~kb}, 13 \mathrm{~kb}, 3.5 \mathrm{~kb} \\\hline \text { SalI }+ \text { HindIII } & 4 \mathrm{~kb}, 5 \mathrm{~kb}, 11 \mathrm{~kb}, 3.5 \mathrm{~kb} \\\hline \text { SalI }+ \text { EcoRI }+ \text { HindIII } & 3 \mathrm{~kb}, 4 \mathrm{~kb}, 5 \mathrm{~kb}, 8 \mathrm{~kb}, 3.5 \mathrm{~kb}\\\hline\end{array}$