Identify if it is ONE-tailed test or TWO-tailed test

>A certain part of a plane has to be manufactured to 0.02 mm accuracy, and quality assurance team tests 10 of the parts to check that they are manufactured correctly.

>A researcher finds that the average lifespan in a country is 78 years old, and wants to test whether people on an island in the country who eat a lot of fish end up living longer.

A random sample of 5000 students were asked whether they prefer a 10 week quarter system or a 15 week semester system. Of the 5000 students asked, 500 students responded. The results of this survey. The choices are: a. can be generalized to the entire student body because the sampling was random. b. should not be generalized to the entire student body because the non-response rate was 90%. c. can be generalized to the entire student body because the margin of error was 4.5%. or d. should not be generalized to the entire student body because the margin of error was 4.5%.