What happens when a s-wave travels through liquid

Which of the following starements is true based on the above information?

Answer quickly! correct answers only! how did an agricultural surplus relate to expanded trade during the high middle ages? a)trade increased because surplus crops could be traded. b)trade decreased because surplus crops were needed to feed local populations. c)trade decreased because surplus crops led to an oversupply of grains that could not be sold. d)trade increased regionally but decreased globally because trade networks had shrunk.

What problem does obeng say that we have in the 21st century? 2. obeng argues that the pace of change has eclipsed the pace of learning. do you agree or disagree? why? 3. what is "smart failure" according to obeng?