Answer: (B) nervous of the slight change he can sense.
Explanation:
 
        
                    
             
        
        
        
The definition of a meter: Distance traversed in vacuum by light in 1/299,792,458 of a second. 
 According to this light travels 299,792,458 meters in a second. A nanosecond is 1 billionth of a second so light travels 299792458 / 1,000,000,000 meters in a nanosecond or 0.299792458m. (In a vacuum).
        
             
        
        
        
Answer: Plethora is a noun. Tranquility is a noun. Conundrum is a noun. 
Explanation:
 
        
             
        
        
        
Answer:
b. went
Explanation:
I think option b is the correct answer. 
Hope it helps.