## Core Concept
The Haldane effect describes the phenomenon where the binding of oxygen to hemoglobin facilitates the release of carbon dioxide. This effect is crucial for understanding how carbon dioxide is transported in the blood. In the presence of the Haldane effect, the uptake of CO2 is enhanced due to the conformational change in hemoglobin that increases its affinity for CO2.

## Why the Correct Answer is Right
In the presence of the Haldane effect, CO2 uptake is 2 ml/100ml of blood in arteries. However, in the absence of the Haldane effect, this uptake would significantly decrease because the conformational change in hemoglobin that facilitates CO2 binding would not occur. Normally, in veins, without the Haldane effect, the CO2 uptake would be less efficient. The correct answer reflects a scenario where, without the Haldane effect, the CO2 uptake would be lower, around 1.5 ml/100ml of blood, indicating a less efficient transport of CO2.

## Why Each Wrong Option is Incorrect
- **Option A:** This option suggests a value that might not accurately reflect the decrease in CO2 uptake without the Haldane effect. Without specific numbers, it's hard to evaluate, but typically, values significantly higher or lower than expected are incorrect.
- **Option B:** Similar to Option A, without the exact value, it's challenging to assess directly. However, if it suggests an increase or a minimal decrease, it would be incorrect because the Haldane effect's absence would decrease CO2 uptake efficiency.
- **Option D:** This option might suggest a value that overestimates the CO2 uptake in the absence of the Haldane effect. Given that the Haldane effect enhances CO2 transport, its absence would lead to a decrease in CO2 uptake, making higher values incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the Haldane effect plays a significant role in the efficient transport of CO2 from tissues to lungs. Its presence allows for a greater uptake of CO2 in venous blood, which is essential for maintaining acid-base balance. Understanding this effect is crucial for managing respiratory and metabolic disorders.

## Correct Answer Line
**Correct Answer: B. 1.5**