The correct answer is C. floats.
Wood is less dense than water, so it floats. This is because the density of an object determines whether it will sink or float in water. Objects that are less dense than water will float, while objects that are more dense than water will sink.
The other options are incorrect because they do not accurately describe the relationship between wood and water. Option A, “float,” is in the present tense, but the question is about the past. Option B, “was floating,” is in the past tense, but the question is about the present. Option D, “floated,” is in the past participle tense, which is used to form perfect tenses and passive voice. In this case, it would be used to say that the wood had floated at some point in the past, but the question is about whether it always floats.
Therefore, the correct answer is C, “floats.”