Answer:
a threat
Step-by-step explanation:
A threat is part of your external environmental analysis and it is basically the opposite of an opportunity. In this case, the threat exists because the new knowledge and technology acquired by Bharti's rival Hutchison can really cause severe damage to the company.
The logic behind this is quite simple, Vodafone has more knowledge and higher technology than Bharti, and probably Bharti's previous competitive advantage resulted from Vodafone's aid. But now, Vodafone is playing for the other team. So your team lost the star quarterback, running back and receiver, they are all playing against you now, and probably do not have very nice feelings towards your team either.
What was once Bharti's greatest strength is now the competition's greatest strength, and that can really damage a company. Generally that is the reason why non-competing clauses are included in many contracts that involve sensitive and important areas.