Answer: a. You should enter if you expect the incumbent to accommodate
Step-by-step explanation:
If you expect the incumbent to be accommodating then it is best to enter the market because you will earn 3 million along with the incumbent.
This will be a gain for the both of you that has a chance of success because fighting you will be to the detriment of the incumbent as they will then stand to lose 10 million like you will as well.
The option of the incumbent being accommodating is the best option for the both of you.