If I go to the pond today, what is the best assumption I can make?

The correct understanding in this scenario is that a reasonable assumption to make when planning to visit the pond would be that there will be other birds present. This is based on common observations around ponds, which often attract a variety of waterfowl and other bird species.

The choice regarding the presence of swans also hinges on context—while swans may be present, it cannot be assumed that swans will definitely be at the pond without additional information. Not all ponds are frequented by swans, and they might not always be there.

When considering the statement about ducks, it is overly definitive to state that there will be no ducks, as ponds typically support the presence of various bird species, including ducks. The claim about all swans being white is also a generalization and does not apply universally—there are species of swans that can be different colors.

Thus, concluding that there will be other birds at the pond today provides the most balanced and plausible assumption, as ponds are natural habitats that often support a diverse avian population.