Consider the situation where the stock price movements during the life of a European option are governed by a two-step binomial tree. Prove that it is not (always) possible to set up a position in the stock and the option that remains riskless for the whole of the life of the option by providing a simple example of a multi-step tree where delta changes.

The prebisch–singer hypothesis concludes that: a. technology lowers the cost of manufactured products, so developing countries should see an increase in their terms of trade. b. developing countries experience a long-run decline in their terms of trade, as the demand for primary products in higher-income countries declines relative to their demand for manufactured goods. c. because of unfair trading practices, labor in developing countries is exploited. d. opec has been responsible for a slowdown in the world's standard of living.