The correct answer is option 4, Teak.

Silkworms, which produce silk, are typically reared on the leaves of the mulberry tree, specifically the white mulberry (Morus alba) species. Mulberry leaves are a primary food source for silkworms as they are rich in nutrients and provide the necessary sustenance for their growth and silk production.

Teak (Tectona grandis), on the other hand, is a type of hardwood tree commonly found in tropical regions. Although teak has various uses such as for furniture, boat building, and construction, its leaves are not used for rearing silkworms. Silkworms have evolved to feed specifically on the leaves of the mulberry tree, and other plant species would not provide the necessary nutrients for their growth.

Therefore, out of the given options, only option 4, Teak, does not have leaves that are used for the rearing of silkworms.