Why are dissolved oxygen concentration is high in the surface waters of the ocean.

Oxygen content is highest at the surface for two main reasons; this is where oxygen dissolves into the ocean from the atmosphere, and the surface water is where oxygen is produced by phytoplankton through photosynthesis

When administering insulin, the most appropriate will be; Insert the needle at a 45-degree angle for injection.
The vial should be gently rotated and vigorous shaking is to be avoided to ensure uniform suspension of the insulin. Insulin may be injected into the subcutaneous tissue of the upper arm and the anterior and lateral aspects of the thigh, buttocks, and abdomen. Intramuscular injection is not recommended for routine injections.