Answer:
A cross-sectional study
Explanation:
A cross-sectional study is an observational study type. In this study the researcher conduct study at a specific point of time. This study analyses the data that is collected from a population or a subset of the population sample.
It is also called a cross-sectional analysis or prevalence study or it is also called a transverse study. In this study, all variables are the same except one variable in the study. But this variable will be constant throughout the study.
This study can be conducted with a different organization. Thus in the above statement, the researcher used cross-sectional research in his study.
Not clear on your question here.. but substance abuse is when you abuse a substance and usually an illegal one such as drugs or alcohol, and when you increase that, you're just using it more? I want to help you but the question is unclear to me!
Fractional distillation
heated crude oil enters a tall fractionating column , which is hot at the bottom and gets cooler towards the top. vapours from the oil rise through the column. vapours condense when they become cool enough.
The correct answer is letter C.
Explanation: Walt Whitman (1819-1892) was an American poet, essayist, and journalist.
A single work of poetry, "Herb Leaves," validates Walt Whitman or recognition as the greatest American poets and one of the leading authors of modernity.
