A retrospective observational study which is used in medical and psychological research by checking historic records .
This study looks backwards in history to examine exposures to suspected risk or protection factors in relation to an outcome that is considered at the beginning of the study.
The given statement says that A statistical analyst obtains data about ankle injuries by examining a hospital's records from the past 3 years.
Hence, this is a retrospective observational study.
that would be the third one 12 ft, 12 ft, 20 ft because the lengths of 12+12 have enough to reach the 20 length compared to 30+30 which would only equal 60 and no more making it a line.
