Answer:
c. A doctoral degree.
Explanation:
A doctorate degree refers to an academic degree (certificate) awarded to a post-graduate student by a tertiary institution (university or college) after the completion of his or her educational Programme. This doctorate programme usually takes a minimum of two (2) years to complete, as well as haven fulfilled the obligation of writing an approved theses.
Most tertiary institutions has made it a prerequisite for all applicants who are interested in being a lecturer (teacher) or research inclined positions, to possess a minimum of a doctorate degree.
Hence, a doctoral degree is necessary for individuals interested in researching and teaching positions.