option n. 选择，选择的权利
【真题重现】2003 Text 3
If railroads charged all customers the same average rate, they argue, shippers who have the option of switching to trucks or other forms of transportation would do so, leaving remaining customers to shoulder the cost of keeping up the line.
optional a. 随意的，可选择的
【真题重现】2003 Text 4
It is said that in England death is pressing, in Canada inevitable and in California optional.
optimistic a. 乐观的
Consumers seem only concerned, not panicked, and many say they remain optimistic about the economy’s long-term prospects,