$21.$Which of the following is NOT correct about machine learning and data mining?

a$)$Computers approximate simple functions from historical data in machine learning

b$)$Machine learning focuses on designing a$/$gorithms that can learn from historical data and make predictions

c$)$Data mining is a cross$-$disciplinary field that aims at discovering properties of data sets.

d$)$Machine learning is not able to be used for data mining.