Is - two billion dollars is a unit, one unit so it is singular and you use the singular verb
think - scientists is a plural, therefore, you must use the plural verb form of think
        
             
        
        
        
Answer:
B. Talk about how you solved a similar work problem in the past.
Explanation:
Hope this helps.
 
        
             
        
        
        
The word commit has different meaning, and I'll just list some of them:
1.to write something down (commit these ides to paper)
2.to pledge to some position, or to state what you stand on an issue (I asked if he was a participate, but he refused to commit himself.
3. to bind yourself, or to obligate ( commit yourself to a cause)
4. to entrust ( I commit myself to you)
5. to do something, perform an action (to commit murder)
6.to commit to custody (he was committed to prison) 
        
             
        
        
        
<span>The international prohibition sign (official name), (also known as a no symbol, no sign, circle-backslash symbol, nay, interdictory circle, or universal no)</span>