Questions: The gives the brain its distinctive shape of bumps and grooves.

The answer is the fourth one (Cerebrum): the cerebrum gives the brain its distinctive shape of bumps and grooves.

Explanation for each option:

1. Cerebellum: This part of the brain is located at the back of the skull and is responsible for coordinating voluntary movements, balance, and posture. It does not give the brain its distinctive shape of bumps and grooves.
2. Brain Stem: The brain stem connects the brain to the spinal cord and controls basic life functions such as breathing, heart rate, and blood pressure. It does not contribute to the brain's distinctive shape of bumps and grooves.
3. Diencephalon: This part of the brain includes structures such as the thalamus and hypothalamus, which are involved in sensory and autonomic functions. It does not give the brain its distinctive shape of bumps and grooves.
4. Cerebrum: The cerebrum is the largest part of the brain and is responsible for higher brain functions such as thought, action, and sensory processing. It is characterized by its convoluted surface, which includes the gyri (bumps) and sulci (grooves), giving the brain its distinctive shape.

Summary: The cerebrum is the part of the brain that gives it its distinctive shape of bumps and grooves.