Which of the following types of research is conducted on multiple occasions over time? a. experimental b. longitudinal c. representative d. cross-sectional

Correct answer choice is :

A longitudinal study is an analysis plan that includes repeated observations of the same variables over the short or long duration of time. It is often a type of observational study, although they can also be structured as longitudinal randomized practices.

well when looking at this if you think about it   negativley and positivley   react with each other and when the first layer gets full they add layers it starts with 2 on the first layer and it constantly goes on until the official number is there