Answer:
Option C, Survey
Explanation:
Lets see the definition of all the three terminologies used here –
a) Observational Study: In this data is collected just by observing the things. The collected data is not used anywhere in any study or research. Observational studies are conducted using surveys. For example - observing the number of students in a class
b) Survey: These are conducted to create a sample data. In a survey, a set of questions are asked to a set of interested people. For example Internet and T.V. surveys, customer satisfaction surveys, type of public opinion poll etc.
c) Experiment: Here a researcher conducts an experiment by controlling some aspect of the study and then records what happens. For example – agar plants are kept in red soil and in absence of sunlight to observe its speed of development.
After realizing the difference between the three terms, the most suitable answer is option C
