Researchers argue that a nation's economic growth is directly proportional to its investment in education. Which of the following, if true, most severely undermines this claim?
Correct: B
A country maintaining economic growth while reducing education spending (Option B) directly contradicts the 'direct proportionality' premise. Option A is a single case that might be an outlier; Option C supports the argument; Option D introduces a competing factor but does not disprove the core claim.