Answer:
The correct answer is - a cross-sectional study.
Step-by-step explanation:
A cross sectional study is a type of study that helps in the analyzing data from a population at particular time. It is helps in to check that if a particular risk exposure will leads to particular result.
In the given case it is the example of the cross sectional study or analysis as it is deals with the effect of the environmental condition to the greenhouse worker to the increased prevalence to respiratory disorder.
Thus, the correct answer is - a cross sectional study.