The examples below are from Maninka, spoken in Guinea, and surrounding countries in West Africa (Bird and Shopen, 1979). In some words, -li is added to a base form (e. g., bo) to create boli. In others, -ni is added to a base form (e. g., don) to create donni. One of the following analyses (a) – (d) best describes this difference's phonetic basis of this difference? boli (“going out”) sigili (“sitting down”)
Donni (“coming in”) tali (“going”)
foli (“greeting”) dumuni (“eating”)
minni (“drinking”) tobili (“cooking”)
Menni (“hearing”) famuni (“understanding”)

If the base form begins with a stop, use -li.
If the base form begins with a fricative, use -ni.

If there is a vowel at the end of the base form, use -li.
If there is a consonant at the end of the base form, use -ni.

If there isn’t a nasal in the base form, use -li.
If there is a nasal in the base form, use -ni.

If there is a liquid in the base form, use -li.
If there is a glide in the base form, use -ni.