A.
ANNs are computer systems made up of large number of interconnected units, each of which can usually compute only one thing. It has been widely used in AI. In computing, an ANN is a program or system which is modeled on the human brain & is designed to imitate the brain's method of functioning, particularly the process of learning.
D.
ANNs allow modeling of nonlinear processes and become a useful tool for solving many problems such as classification, clustering, dimension reduction, regression, structured prediction, machine translation, anomaly detection, pattern recognition, decision-making, computer vision, visualization, & others.