How would you go about answering the question: "If successful in securing a training contract after the Summer Internship, what do you anticipate will be the key challenges of the International Training Programme for you? How would you approach these challenges, and what resources or support do you believe you would need to overcome them?"
How closely tied to the firm does it have to be and how would one make themselves stand out (since I imagine everyone might end up saying similar things)?
Tie it to you first - you should focus on your challenges, rather than generically what most trainees could say.
Then tie it to the firm. Try to be specific about the firm's resources you could use. Name them using the terminology the firm uses - be specific as possible.
Ensure your answer is forward looking rather than relying on past examples to show your skills. You should picture yourself in the firm with the challenges you identify rather than talking about how your previous experiences have set you up well (if that is the case, it would not be a challenge for you).