Answer: exponential growth
Step-by-step explanation:
From the given table, Energy taken by billionth in 1 sec 
Energy taken by billionth in 2 sec 
Energy taken by billionth in 3 sec 
Energy taken by billionth in 4 sec 
Now, 
Since, they all have common ratio = 2.37
Hence there is a exponential growth of billionth.
[In exponential growth the ratio of the rate of change of the variable to its current size remains constant over time ]