BQ4050: How to deal with unused pin?

Tool/software:

Good day,

About HW design of BQ4050 unused pins,

I plan to not use No. 7,11~15,17,20~24,29,30.

About each unused pins above,

Please let me know the implementation in 3 options.

 1. leave open

 2. pull-down resistors

 3. connect Vss directly

thanks,