3. All mammals have a brain. Kangaroo is mammal. It has a brain. This is an example of:

a. Inductive reasoning
b. Deductive reasoning
c. Both a and b
d. None

b. Deductive reasoning

b. Deductive reasoning

To determine the correct answer, let's understand the difference between inductive and deductive reasoning.

Inductive reasoning involves making generalizations or conclusions based on specific observations or examples. It moves from specific instances to general principles. On the other hand, deductive reasoning involves drawing specific conclusions based on general principles or premises. It moves from general principles to specific instances.

In the given example, we are presented with two premises:

1. All mammals have a brain.
2. Kangaroo is a mammal.

Based on these premises, we can make the conclusion that the kangaroo also has a brain.

Now, let's apply the concepts of inductive and deductive reasoning to determine the correct answer:

- Inductive reasoning: In this case, we would be inferring a general principle from specific observations or examples. However, the example does not provide enough information or observations to create a generalization about all mammals having a brain. Therefore, it does not fit the definition of inductive reasoning.

- Deductive reasoning: In this case, we are drawing a specific conclusion based on the general principle that all mammals have a brain. We are applying a general principle to reach a specific conclusion. This aligns with the definition of deductive reasoning.

Based on the above analysis, the correct answer is:

b. Deductive reasoning