The kind of statistical study described in this case is a retrospective study (third option).
What is a retrospective study?
This is a type of research study that aims at understanding the past of the phenomenon studied. Due to this, retrospective studies focus on looking backward in time and analyzing data that has already been collected either by the investigator or other investigators in the same field.
This design applies to the study described as data that was already collected was analyzed to understand the relationship between soil and cancer.