**Core Concept**
The question tests the student's knowledge of local anesthetic properties and their interactions with vasoconstrictors like adrenaline. Local anesthetics work by blocking sodium channels, which prevents nerve depolarization and subsequent pain transmission.

**Why the Correct Answer is Right**
Lidocaine is a local anesthetic that can be used without adrenaline (epinephrine) because it has a moderate duration of action and does not significantly reduce blood flow. Adrenaline is often added to local anesthetics to prolong their duration of action by causing vasoconstriction, which slows the absorption of the anesthetic into the bloodstream. However, lidocaine's moderate duration of action makes adrenaline unnecessary.

**Why Each Wrong Option is Incorrect**
**Option A:** Bupivacaine - Bupivacaine is a long-acting local anesthetic that benefits from the addition of adrenaline to prolong its duration of action, making it a wrong choice.
**Option B:** Mepivacaine - Mepivacaine is similar to lidocaine but has a slightly shorter duration of action, making adrenaline a useful adjunct to prolong its effects, making it a wrong choice.
**Option C:** Procaine - Procaine is a short-acting local anesthetic that is often used in combination with adrenaline to prolong its duration of action, making it a wrong choice.

**Clinical Pearl / High-Yield Fact**
When choosing a local anesthetic, consider the duration of action and the desired effect. If a short duration is sufficient, adrenaline may not be necessary, but if a longer duration is required, adrenaline can be a useful addition.

**Correct Answer: D. Lidocaine**