A – Correct
Competition is the general focus of the passage. The last sentence “the jockeying offers…opportunities for consumers” suggests that competition is good for consumers.
B – Wrong
‘Have’ is a very strong verb and hence, this is wrong.
C – Wrong
This is not a rule that mature companies cannot compete with emerging ones.
D – Wrong
The passage only suggests that the other three companies could form an alliance. There is no guarantee that none of the three companies will not merge with Google.
E – Wrong
There could be other companies that pose a threat to Microsoft.