Given the question: Information:  - George Brettingham Sowerby I (12 August 1788  26 July 1854) was a British naturalist, illustrator, and conchologist.  - George Brettingham Sowerby III ( 1843 -- 1921 ) was a British conchologist , publisher , and illustrator . He , too , worked ( like his father George Brettingham Sowerby II and his grandfather George Brettingham Sowerby I ) on the Thesaurus Conchyliorium , a comprehensive , beautifully illustrated work on molluscs . He was colour blind , and thus his daughter did most of the colouring of his engravings .  - George Brettingham Sowerby II (1812  26 July 1884) was a British naturalist, illustrator, and conchologist. Together with his father, George Brettingham Sowerby I, he published the "Thesaurus Conchyliorum" and other illustrated works on molluscs. He was the father of George Brettingham Sowerby III, also a malacologist.    After reading the paragraphs above, we are interested in knowing the entity with which 'george brettingham sowerby iii' exhibits the relationship of 'occupation'. Find the answer from the choices below.  Choices: - illustrator  - malacologist  - naturalist  - publisher
The answer is:
malacologist