The sun has six layers (or regions). What is the name of the innermost region

Waves are used in many practical applications to support work, entertainment, and health. one example is the use of ultrasound imaging to safely track the development of a growing fetus. what is a specific example of a practical application of waves in medicine, entertainment, safety, or other fields? provide a brief explanation of how the properties of waves are useful to that application.

What is a neurotransmitter involved in mood reward, addiction, and motor behaviors?

Gordon is going for a run through the park, but it is cold outside. the low outside temperature could affect his personal safety.