Question

Dominican soldiers could tell the nationality of a Haitian by

their facial features.
the way they pronounced words.
the type of clothing they wore.
their way of greeting strangers.

Answer 1

the way they pronounced words.

Dominican soldiers famously used a pronunciation test (often asking people to say "perejil" — parsley); nonnative speakers with Haitian/French/Creole accents were identified as Haitian.