سَلَّمْتُ عَلَى طَالِبَاتٍ.
Translation: I greeted female students.
Grammatical analysis
سَلَّمْتُ: past-tense verb with first-person subject pronoun.
عَلَى: preposition.
طَالِبَاتٍ: genitive noun, with kasra.
Compare with رَأَيْتُ طَالِبَاتٍ. Both endings contain kasra, but one noun is accusative and the other genitive.