The correct option is C Schleiden
In 1838, German botanist, Matthias Schleiden found that all plant tissues are made up of cells which have been essentially similar structure. German zoologist, Theodor Schwann in 1839 working independently observed that animal cells do not have cell walls but are otherwise similar amongst themselves. He put forward cell hypothesis which states that bodies of animal and plants are made up of cells. Schleiden and Schwann in 1839 compared their findings and formulated cell theory.