Which additional word in the sentence, if any, should be followed by a comma?

The solution, I believe will be found by examining the problem logically.

A.
examining

B.
believe

C.
found

D.
There is no error in comma usage

Question

Which additional word in the sentence, if any, should be followed by a comma? 

The solution, I believe will be found by examining the problem logically.
  
 
 

 
 

  

  A. 
  examining   
   

 
 

  

  B. 
  believe   
   

 
 

  

  C. 
  found   
   

 
 

  

  D. 
  There is no error in comma usage

anonymous · Answer

@.TH3_M0NST3R. I say D

.th3_m0nst3r. · Answer

Nope, it's B. 
Because you'd have to pause after saying believe. c:

anonymous · Answer

K thanks! I think I have two more

.th3_m0nst3r. · Answer

Okay, make em' quick because my internet will shut off in 15 minutes. :p