To answer the question,
1, as a member of group B, I should first focus my attention on my job in group B
2, If my T/L asked my suggestion for helping group A, I would ask a question why group A could not meet their deadline before I could give a solution.
For example, if group A need more people to finish its project, group B may temporarily have some one work for group A if it does not affect group B
however, if group A has some technical difficulties, then it does not matter how many people working in the group. In this case, the team should look for other resources to get one who can fix the technical problem
So, the answer I think is open, and the worst answer is to directly give a solution without analytical thinking.