The correct answer is option 3: Oxalic acid.
Option 1: Acetic acid is not found in abundance in tomatoes. Acetic acid is the main component of vinegar and is not a naturally occurring acid in tomatoes.
Option 2: Citric acid is a common acid found in many citrus fruits like lemons, oranges, and grapefruits. Although tomatoes do contain small amounts of citric acid, it is not found in abundance compared to other acids.
Option 3: Oxalic acid is a naturally occurring acid that is found in various plants, including tomatoes. It is present in relatively large amounts in tomatoes, especially in the leaves and stems. However, it should be noted that the concentration of oxalic acid in the edible part of tomatoes (such as the fruit) is relatively low and not harmful to consume.
Option 4: Tartaric acid is a naturally occurring acid that is found in grapes and some other fruits. It is commonly used in winemaking, but it is not found in abundance in tomatoes.
Therefore, the correct answer is option 3: Oxalic acid.