Strobili or cones are found in:
Correct option is C. Equisetum
Strobili or cones are the dense and compact structures present on non-flowering plants. They contain sporangia and perform function of protecting spores from wild animals and harsh conditions of environment.
In Equisetum, the strobili are present at the terminal position on stem. Equisetum are also known as horsetails and come under the category of ferns.
Thus, the correct answer is (C).