Q: Why do twentieth century advances not seem sustainable?
(a)They do not meet the human needs
(b)Due to the increased cost of agricultural production
(c)Because they are outdated for the current times
(d)They are useful, but intensive
Correct Answer: (b)
The correct answer is (d): They are useful, but intensive. Subject: English Language | Sub-topic: Grammar & Vocabulary Note: This answer was determined through AI-based research. Verify against the official answer key when available.