The correct answer is option 1, Oesophagus.

The inner lining of the oesophagus is made up of stratified squamous epithelial cells. Epithelial cells are the main type of cells that form the tissue lining of various organs and structures in the body.

Option 2, Small intestine, is incorrect because the inner lining of the small intestine is made up of simple columnar epithelial cells. These cells function to absorb nutrients from the digested food.

Option 3, Ducts of salivary gland, is also incorrect. The ducts of salivary glands are lined by a different type of epithelial cells called cuboidal or columnar epithelium.

Option 4, Kidney, is incorrect as well. The inner lining of the kidney is composed of specialized cells called renal tubular epithelial cells, which play a crucial role in the filtration and reabsorption of waste products in the urine.

In summary, the correct answer is option 1, oesophagus, because this is where stratified squamous epithelial cells are found in the inner lining.