Answer:
The sentence that means "they greeted each other" in Spanish is:
C) Se saludaron
Step-by-step explanation:
Yo me salude/ Tu te saludaste/ Él se saludo/ Ella se saludo/ Nosotros nos saludamos/ Ellos se saludaron.
A reciprocal verb is one that conjugates a pronoun according to the subject and syntactic function.
The verb "Ellos" can be changed by the reciprocal verb "Se" in the sentence.
And, "greeted each other" is in the past tense, so in Spanish this is translated as "Saludaron"