Most preferred answer here is Answer B Decision trees
Regression is generally used to predict a particular value like 2.3 , 4,3 as output ,even though logistic regression can be used to predict binary output variable .
Clustering is unsupervised learning so it is preferred for input data which are not more related and form them into groups .
Decision tree comes under supervised learning and is mostly used than regression For example GBDT is most used technique in machine learning apart from Deep learning algos
associativity is defintitely not possible .