Here's why:
* la is the feminine singular definite article (the)
* estudiante is the feminine singular noun (student)
* las is the feminine plural definite article (the)
* estudiantes is the feminine plural noun (students)
Here's why:
* la is the feminine singular definite article (the)
* estudiante is the feminine singular noun (student)
* las is the feminine plural definite article (the)
* estudiantes is the feminine plural noun (students)