Anne's excellent spelling grades are testament to her understanding of 'Orthography'. It is the correct option as it refers to the conventional spelling system of a language and is sustainable with the context of spelling grades.
"Anne's excellent spelling grades are testament to her grasp of ________." - is C. Orthography. Orthography refers to the conventional spelling system of a language. As Anne has high spelling grades, this represents a good understanding of orthography.
Anne's grasp of orthography indicates that she's able to comprehend and apply standard spelling rules and patterns in English, which results in her excellent grades. The other options (A. Saturnine B. Paleontology D. Shibboleth) are unrelated to the context of spelling. For instance, Paleontology is the study of the history of life on Earth through the examination of plant and animal fossils. Shibboleth and Saturnine are words with meanings irrelevant to spelling skills. Therefore, these aren't valid answers to the given question.
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