VT70 String

I'm an intermediate player planning on purchasing Voltric 70 after I broke my Victor BS35. I'm little overwhelmed choosing the string and string-tension and need some help.

The string tension mentioned for the racket is from 20-24 lbs. What is an optimum tension for this racket?

The strings listed are Yonex BG-65, BG-66 ultimate, BG-70 Pro, BG-68 Ti, BG-80, BG-80 Power, BG 85, NBG 95 Nanogy (gold, silver), NBG 98 Nanogy (gold, silver), NBG 99 Nanogy. Please help me choose the right one.

Thanks,
howe