Answer:
The correct option is B.
Step-by-step explanation:
A cohort study can be used in medicine to draw comparisons between a group with similar characteristics and a much larger group where the initial group is drawn from. The basis of comparison usually defines the type of cohort study been discussed. The question compared individuals from a location as against those from a larger surrounding, thus this type of cohort study can be referred to as a geographical cohort study.
NOTE: It isn't a clinical trial as none of the two compared groups was given any form of treatment or dose.