There are two sources that serve as the foundation for conducting research on learning. The first source addresses characteristics of knowledge itself and the different ways in which we learn things. The second source focuses on what goes on in our minds and how that is theoretically represented.

There are two sources that serve as the foundation for conducting research on learning. The first source addresses characteristics of knowledge itself and the different ways in which we learn things. The second source focuses on what goes on in our minds and how that is theoretically represented.

Step-by-step explanation:

The investigations on the process of how we learn have led to two main sources:

- Acquisition of knowledge which involves assimilation or understanding, storage and retrieval

- The second source belongs to a modern learning cognitive psychology, neuroscience, and cognitive science theories on mental representation, which concerns about the build up of an internal symbol or cognitive representation to hypothetically figure out, external reality.

a is the right answer