Explanation:
Downwelling is the process where cold and heavy dense water moves down into the ocean floor and warm light dense water rises to the surface. As a result of downwelling, the water high dense water which rises to the water surface brings the oxygen rich water to the surface for the marine animals to breathe properly. Also when the ocean surface water becomes little warmer it becomes a little comfortable for the marine animals to survive in this severely cold climatic conditions at polar reasons.
Substract two consecutive terms of the sequence to see if there is a common difference:

As we can see, there is a common difference of -6.
Then, if a number of the sequence is given, the next one can be found by adding -6 (which is the same as subtracting 6).
Notice that the first term of the sequence is 3.
Then, the rule for the sequence is to start with 3 and add -6 repeatedly.
Therefore, the correct choice is option A) Start with 3 and add -6 repeatedly.
The car will gain new momentum if it's velocity is doubled or tripled.