Why did the elevation of land is measured from the level of sea?

Doing the text now can someone me

Erika is a human resource manager at bluetel inc., a software company. she receives a call from an hr manager at another software company asking about marshall, a software engineer who used to work at bluetel and has applied for a job at the caller's company. erika checks the company's records and sees that a coworker had accused marshall of racial discrimination, but an investigation did not turn up any evidence to support the charge. marshall left the company two months later, saying he was no longer comfortable there. erika is concerned about sharing the details of this situation with the caller. if telling the information to the caller leads to the other company not hiring marshall, what potentially unlawful behavior could marshall accuse bluetel of engaging in?

For each of the following examples of data, determine which scale of measurement is used. a) the number of miles joggers run per week. b) the starting salaries of graduates of mba programs c) the months in which a firm's employees choose to take their vacations. d) the final letter grades received by students in a math course.