Final answer:
An increase in the price of tea, a substitute for coffee, would shift the demand curve for coffee from d₁ to d₂, as consumers would turn to coffee as an alternative.
Step-by-step explanation:
The demand for a normal good, such as coffee, will shift due to various factors. In this scenario, we are considering what would cause the demand curve for coffee to shift from d₁ to d₂. An increase in the price of tea, which is a substitute for coffee, would cause consumers to buy more coffee instead of tea, thus shifting the demand curve for coffee to the right, from d₁ to d₂. This shift is a response to a change in the relative price of the substitute, not a change in the price of the coffee itself.
Therefore, the correct answer to what would shift the demand for coffee from d₁ to d₂ is option 1). Options 2), 3), and 4) are incorrect because they relate to the price of coffee or consumer income, which are not correct in the context of the question.