There are several information's of immense importance already given in the question. Based on those information's the answer can be easily deduced.
Initial number of bacteria in the culture = 1000
Number of bacteria after t hours = 1000 (2)^t
Then
1000 (2)^t = 50000
2 ^t = 50
t = 5.6
I hope the procedure is clear enough for you to understand.
Is there a picture to go with this?
Answer: Adaptive immunity
Explanation:
The adaptive immunity is also known as acquired immunity. It is a sub system of the overall immunity.
It can defined as the immunity which is not present in the body when we are born. It develops in the body when it is exposed to the pathogens no matter it is natural or artificial.
The acquired immunity can develop in the body and makes the body susceptible to infections and develops prevention for the next time when the body will be exposed for the next time.
The correct is the first answer.