Each guest had to wear either a red or white tunic
Some guests were allowed to use a golden ribbon with their tunic
250 guests did not wear a golden ribbon
240 guests wore red tunics
How many guests wore a white tunic without a golden ribbon?

Statement 1
100 guests wore a white tunic with a golden ribbon ; information given is not enough to answer this statement we don't know total number of guest that wore white to the party. statement 1 is not SUFFICIENT.

Statement 2
150 guests wore a red tunic with a golden ribbon
No of guests with red tunic and no ribbon =240 - 150 = 90 guests
Total no of guests without ribbon = 250
If 90 more red tunic without ribbon, then guest that wore white ribbon = 250 - 90 = 160 guests.
Statement 2 alone is SUFFICIENT.

$$answer\ is\ Option\ B$$