**Core Concept**
Bier's block is a type of systemic toxicity that can occur due to the accidental intravascular injection of a local anesthetic agent. This condition is characterized by the rapid onset of central nervous system and cardiovascular system toxicity. The primary concern in Bier's block is the potential for seizures, cardiac arrhythmias, and even cardiac arrest.

**Why the Correct Answer is Right**
The correct answer is related to the administration of local anesthetics through a peripheral nerve block or regional anesthesia. Bier's block specifically involves the injection of a local anesthetic agent into a vein, usually in the upper extremity, to achieve a nerve block. This technique requires precise placement of the needle and monitoring of the patient's vital signs to prevent systemic toxicity.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as the question is incomplete.
**Option B:** This option is not relevant to Bier's block, which is a specific type of systemic toxicity caused by intravascular injection of local anesthetics.
**Option C:** This option might be related to a different type of regional anesthesia or nerve block, but it is not the correct answer for Bier's block.
**Option D:** This option is also not relevant to Bier's block and might be related to a different type of anesthesia or injection technique.

**Clinical Pearl / High-Yield Fact**
To avoid Bier's block, it is essential to use a tourniquet to occlude the blood flow to the limb before injecting the local anesthetic agent. This helps prevent accidental intravascular injection and reduces the risk of systemic toxicity.

**Correct Answer:** C. Intravenous