Well obviously you dont directly want the answer but the method to solve it if not so directly go to the pic.

The trick is to locate different hydrogens . Each one will produce a different mono chloro derivative .

Firstly there's a 3° hydrogen then there's a 2° H and then there are 3 methyl groups all having 1°H but the surprise is all the 3 methyl groups are not the same because two of them are bonded to 3° carbon while the other one is bonded to a 2° carbon .

Replace these H atoms by Cl check the stereochemistry of the compound and you have your answer.