Which statement best defines a phoneme? A
It is the smallest unit of sound.
OB.
It is the smallest unit of meaning.
O c.
It is a set of rules to help people derive meaning from a given sound.
D.
It is the study of sentences.

A - It is the smallest unit of sound

Explanation:

A phoneme is defined as "The smallest unit of speech distinguishing one word from another, as the element "p" in "tap" that separates the word from "tag" or "tab"."

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step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.