Which of the following is not an organic acid ?

The acids which produced by animals/plants are called organic acids. HCl is a mineral acid.

Citric acid is found in citrus fruits, especially juices of lemons and limes.

Oxalic acids is found in many plants, especially leafy greens, vegetables, etc..

Acetic acid is the byproduct of fermentation. Vinegar is usually 3-9% acetic acid.