What is the critical value t' for constructing a 90% confidence interval for a mean from a sample size of n=18 observations?

Which of the following best describes the difference between “autobiography” and “memoir”? a. autobiography is written about the author's own interpretation of events; memoir is a written interpretation of events. b. memoir covers a particular time in the writer’s life or recounts life events around one or two themes; autobiography covers the entire story of the author's life and has multiple themes. c. autobiography covers the entire story of the writer's life and has multiple themes; memoir is a shorter written work with one theme. d. autobiography covers entire story of the writer's life and has multiple themes; memoir is the writer’s random memories about past experiences.