Answer:
Step-by-step explanation:
The spelling of "etiology" follows the guideline for adding a suffix that begins with a vowel to a combining form. The combining form "etio-" refers to the cause or origin of something, and the suffix "-logy" refers to the study of something. When adding a suffix that begins with a vowel to a combining form, it is generally recommended to keep the combining vowel in place to avoid awkward or difficult-to-pronounce combinations. For example, the word "pyrogenic" follows this guideline, with the combining form "pyro-" (referring to fire or heat) and the suffix "-genic" (referring to something that produces or generates something else).
The spelling of "ni" is not a medical word, and the spelling of "necro-" and "diag-" are not combining forms. "Necrosis" and "diagnosis" do not follow the guideline for adding a suffix that begins with a vowel to a combining form, as the combining vowels are dropped when the suffixes are added.
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