Given the following constructor, identify the correct way(s) to instantiate an object.
class Student:
def __init__( self,first_name, last_name, sub='Math') :
self.sub= sub
self.first_name = first_name
self. last_name = last_name
a. Student('Daniel', 'Radlad', 'Literature')
b. Student(sub= 'Science')
c. Student('Daniel', 'Radlad')
d. Student()
e. student('Daniel', 'Radlad')
f. Student('Daniel')