At what point can the president express their opinion on a matter?

The correct choice indicates that the president cannot express their opinion during discussions. In many parliamentary procedures, the presiding officer, such as the president in this context, has a role that is primarily to facilitate discussion and ensure that the meeting runs smoothly. By refraining from participating in debates or expressing personal opinions, the president maintains neutrality and ensures that all voices are heard without bias. This practice also helps to prevent any undue influence over the decisions being discussed and allows members to contribute freely.

In contrast, the other choices imply situations where the president could express their opinion, which would be inconsistent with the role's requirement to remain impartial during deliberations. By preserving this neutrality, the integrity of the meeting and the decision-making process is upheld.