The correct answer is: D. All of the mentioned
Causal analysis is a statistical process for estimating the relationships among variables. It is used to determine whether one variable causes another, or whether there is a correlation between the two variables.
Regression analysis is a statistical method that is used to estimate the relationship between two or more variables. It is used to predict the value of one variable based on the values of the other variables.
Multivariate analysis is a statistical method that is used to analyze the relationships among multiple variables. It is used to identify the variables that are most important in explaining the variation in another variable.
All of these methods are used to estimate the relationships among variables. They can be used to answer different questions, but they all use statistical methods to estimate the relationships.