The question asks which of the given tissues is classified as an elastomer. Let's understand the concept of elastomers to identify the correct answer.

Elastomers: Elastomers are materials that can undergo significant stretching and then return to their original shape. This property is known as elasticity. In biological terms, certain tissues in the body have elastic properties to accommodate stretching and contracting with minimal energy loss.

Now, let's evaluate the options:

1. Tissue in Veins: While veins have some elasticity to help maintain blood flow, they are not primarily known for their elastomeric properties.
2. Tissue in Kidney: The kidney's tissues perform a filtration function and do not need elastomeric properties for their primary functions.
3. Tissue in Pancreas: The pancreas is a glandular organ involved in digestive and hormonal functions, not requiring elastomeric properties.
4. Tissue of Aorta: The aorta is the largest artery in the body, designed to handle high pressure from the heart. It is highly elastic, allowing it to expand and contract with each heartbeat. This elasticity is crucial for maintaining stable blood flow, making it a classical example of an elastomeric tissue.

From the analysis, we conclude that the Tissue of Aorta is classified as an elastomer due to its essential elastic properties that enable it to stretch and recoil effectively, maintaining efficient blood circulation. Therefore, the correct answer is:

Correct Answer: Tissue of Aorta