A student measuring how gasoline prices change records the cost of gas at 10 randomly selected stations in her hometown. One week later, she records the price again at the same 10 stations. She wants to test the hypothesis that prices have increased and subtracts week 2 from week 1. What is an appropriate alternative hypothesis?

Ha = μ(diff)<0

Explanation: The alternative hypothesis are usually established in other to differ on the stance of the null hypothesis. The alternative hypothesis usually takes the form of establishing that a change is actually taking place. The alternative hypothesis in the context above, will aim to show that the difference between prices of week one and week two is not zero. That means that sample mean of prices of week one minus mean prices of week one is less than or zero. Or mean prices of prices of week one minus mean prices of prices during week 2 is greater than zero. The alternative hypothesis is usually depicted with the (H1 or Ha) symbol.

i think it's b or c hope this