When administering insulin, what would be most appropriate?

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. 

They are both used to view parts of the cell