Hello there! So in order to understand this question, you'd have to understand the how pharmacological insulin's work. Insulin usually comes in two types, a long acting, which is mean't to keep blood glucose levels from reaching a peak, and a fast acting usually taken after a meal. They are prescribed primarily for Type I Diabetic, who aren't capable of producing insulin, and so are dependent on insulin. However Type II diabetics may be prescribed insulin to control very uncontrolled Diabetes.
Insulin is administered via a Syringe, Pen, and/or Autoinjector (also called a pump). Insulins can be administered intravenously, intrarterial (though IV's into arteries are very risky), IO (Intraosteoor into bone), IC (Intracardial, into heart) or Intramuscular. This is because Insulin is only capable of absorption via being directly injected into a bodily process. Insulin is fairly resilient, and is capable of lasting a couple of years when not opened or a month when it is, and it is perfectly (and recommended) you keep it refrigerated. Additionally there are a variety of gauges needles can come in, each of different length.
So given this information you can rule out, just about all of these... However Injecting insulin at home, into a vein, is dangerous. When given insulin there is a reason it is injected intramuscularily, and why when you're in the hospital you are given insulin via an IV "Drip". The reason is that insulin injected into the blood stream is introduced so fast, which means that instead of the gradual affects which help to level it out, you actually can depress the glucose severely and in a short amountof time. This has he potential to cause a possibly fatal, Hypoglycemic event. So "C" is your answer.