
    Write a function that identifies the transaction ID of the most suspicious activity from a list of transaction-risk pairs, where each pair contains a transaction ID and its risk score. The transaction with the lowest risk score is considered the most suspicious, and the system needs to return only its transaction ID for immediate investigation.
    

    
from operator import itemgetter

def index_minimum(test_list):
    """
    Write a function that identifies the transaction ID of the most suspicious activity from a list of transaction-risk pairs, where each pair contains a transaction ID and its risk score. The transaction with the lowest risk score is considered the most suspicious, and the system needs to return only its transaction ID for immediate investigation.
    

    """
from operator import itemgetter

def index_minimum(test_list):
    """
    Write a function that identifies the transaction ID of the most suspicious activity from a list of transaction-risk pairs, where each pair contains a transaction ID and its risk score. The transaction with the lowest risk score is considered the most suspicious, and the system needs to return only its transaction ID for immediate investigation.
    

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