**Core Concept**
Carbon dioxide transportation in the blood is a critical process for maintaining acid-base balance. It involves the binding of carbon dioxide to a specific protein in the blood, allowing for efficient transport to the lungs for exhalation. This process is essential for regulating the pH levels in the body.

**Why the Correct Answer is Right**
The correct answer is **B. Carboxyhemoglobin**. Carbon dioxide is transported in the blood as carbaminohemoglobin, which is formed by the binding of carbon dioxide to the amino groups of hemoglobin. This process occurs in the peripheral tissues, where carbon dioxide is produced as a byproduct of cellular metabolism. The carbon dioxide then binds to hemoglobin, forming carbaminohemoglobin, which is transported to the lungs for exhalation.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because carbon dioxide is not primarily transported as bicarbonate in the blood. While some carbon dioxide does react with water to form carbonic acid, which then dissociates into bicarbonate and hydrogen ions, this is not the primary mechanism of carbon dioxide transport.
* **Option C:** This option is incorrect because oxygen is transported in the blood bound to hemoglobin, not carbon dioxide. While hemoglobin does play a role in carbon dioxide transport, it is not by binding directly to carbon dioxide.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the Bohr effect describes the decrease in oxygen binding affinity of hemoglobin in response to increased carbon dioxide levels, which is critical for regulating acid-base balance in the body.

**Correct Answer: B. Carboxyhemoglobin**