Final answer:
Regular insulin is the only type that can be given via IV. Insulin injections decrease blood glucose levels by facilitating glucose transport and storage after a meal. Recombinant insulin is a protein produced by molecular cloning, not derived from pigs or the human pancreas.
Step-by-step explanation:
The only type of insulin that can be given intravenously (IV) is regular insulin. Other forms of insulin, such as NPH, long-acting, and rapid-acting, are designed to be absorbed over time and thus are typically administered subcutaneously. Regular insulin, however, has a short action profile and is appropriate for IV use, which is necessary in certain clinical situations such as diabetic ketoacidosis where fast-acting blood glucose control is imperative.
Regarding insulin injections, it is important to clarify that they are used to decrease blood glucose levels after consuming a meal, by allowing transport and storage of glucose (Option d). This helps to manage and regulate blood sugar levels in individuals with diabetes.
Furthermore, insulin produced by molecular cloning is known as recombinant insulin (Option b). This modern form of insulin is not of pig origin or made by the human pancreas but rather is a recombinant protein created through recombinant DNA techniques.