
    Given a collection of learning style identifiers paired with their effectiveness scores, determine the learning style that resulted in the lowest difficulty score for students. Each learning style is represented by a unique identifier and is paired with a numerical effectiveness score, where lower scores indicate better student performance.
    

    
from operator import itemgetter

def index_minimum(test_list):
    """
    Given a collection of learning style identifiers paired with their effectiveness scores, determine the learning style that resulted in the lowest difficulty score for students. Each learning style is represented by a unique identifier and is paired with a numerical effectiveness score, where lower scores indicate better student performance.
    

    """
from operator import itemgetter

def index_minimum(test_list):
    """
    Given a collection of learning style identifiers paired with their effectiveness scores, determine the learning style that resulted in the lowest difficulty score for students. Each learning style is represented by a unique identifier and is paired with a numerical effectiveness score, where lower scores indicate better student performance.
    

    """
    res = min(test_list, key=itemgetter(1))[0]
    return res