Answer:
option (B) 9.10%
Step-by-step explanation:
Data provided in the question: 
Total market value of a company’s stock = $650 million 
Total market value of the company’s debt = $150 million
Cost of Equity, ke = 10% = 0.10
 Cost of Debt, kd = 8% = 0.08
 Corporate tax rate, T = 35%
Now,
WACC = 

on substituting the respective value, we get
WACC = 

= 0.08 × 0.65 × 0.1875 + 0.10 × 0.8125
= 0.00975 + 0.08125
= 0.091 
or 
= 0.091 × 100% = 9.10%
Hence,
The correct answer is option (B) 9.10%