Answer
Circulation of Blood in a Frog
The heart of a frog pumps blood to all parts of the body through arteries. These arteries carry oxygenated blood from the heart to the tissues.
In contrast, veins collect deoxygenated blood from different parts of the body and return it to the heart.
The major vein responsible for carrying deoxygenated blood back to the heart is the vena cava.
Therefore, the correct answer is: vena cava.