The correct answer is C. associates in some action.
The idiom “hand in glove” means to be closely associated with someone, especially in a dishonest or criminal activity. In this case, the secretary and the treasurer are likely working together to achieve some common goal, whether it is legal or illegal.
Option A is incorrect because it is not necessarily true that people who are hand in glove are very good friends. They may be friends, but they may also be simply associates or colleagues.
Option B is incorrect because it is not necessarily true that people who are hand in glove are constantly fighting. They may be working together in a cooperative way, or they may be working together in a competitive way.
Option D is incorrect because it is not necessarily true that people who are hand in glove are suspicious of each other. They may trust each other completely, or they may simply be aware of the potential for conflict.