In the following sentences, what does "leave" mean and what does "which" refer to?

Once you have that foundation in place, you can experiment around the edges with your own stock choices. Keep 90% of your stock money in an index fund, leaving 10% with which to try picking your own stocks.

Question

In the following sentences, what does "leave" mean and what does "which" refer to?

Once you have that foundation in place, you can experiment around the edges with your own stock choices. Keep 90% of your stock money in an index fund, leaving 10% with which to try picking your own stocks.

Answer

There is 10% remaining or left over after you keep 90% in the index fund. 'Which' is the 10% - you can try picking your own stocks with that 10%.

Answer

Claire's is the only correct answer - the others seem to have it backwards.     Other exmples:

There were three sandwiches. He ate two, leaving one for his sister. 
He works five days a week, leaving two to relax and do errands.

Answer

Hi, 
"leave" = Keeping 90% of your portfolio value in ETF.

"Which" = that remaining 10% you can use for picking stocks by yourself reducing risk.

Answer

leave like making it 90% and the rest