The hormone that regulates blood sugar level is:

**The reasoning** Insulin is produced by the **pancreas** (specifically, the beta cells in the islets of Langerhans). Its primary job is to regulate blood glucose levels by: 1. Allowing glucose to enter cells from the bloodstream 2. Signaling the liver to store excess glucose as glycogen 3. Lowering blood sugar when it's too high (like after eating) When insulin is insufficient or ineffective, you get diabetes — a condition where blood sugar remains dangerously high. This is why diabetic patients often need insulin injections. **Why the wrong options tempt you** - **Adrenaline** does affect blood sugar (raises it during stress/emergency), but it's not the *regulator* — it's for "fight or flight" responses. - **Thyroxine** controls metabolism and growth rate, not specifically blood sugar. - **Oxytocin** triggers uterine contractions during childbirth and milk release — completely unrelated to glucose. **Quick takeaway** Think: **"IN-sulin lets glucose IN"** — it's the key that unlocks cells to absorb sugar and keep your blood levels balanced. Pancreas = insulin = blood sugar control. Lock that in!