Why is it mandatory to underline genus and species names separately when writing scientific names by hand?

Correct answer: It is the accepted substitute for italics when a scientific name is written by hand

Correct answer: A. In a printed scientific name, the genus and specific epithet are conventionally written in italics, for example Mangifera indica. Handwriting normally cannot reproduce typographical italics reliably, so each word is underlined separately: Mangifera and indica receive separate underline marks. Separate underlining shows that the two words together form a binomial scientific name and preserves the distinction between the genus and the specific epithet. B is wrong because this is a nomenclatural convention, not merely an examination preference. C is wrong because the purpose is standardisation, not decoration. D is wrong because the convention is taught and used in scientific writing. The genus begins with a capital letter, while the specific epithet begins with a lowercase letter. Memory cue: “Printed—italic; handwritten—underline.”