Answer:
"beginning" is the gerund in the sentence.
Step-by-step explanation:
A gerund is a word, a verb that acts or functions as a noun in the sentence. Also, the verb will end with an "-ing", thus making the verb a noun.
In the given sentence, the verb is "begin", and added with an '-ing' functions as a noun in the sentence. So, the word "beginning" acts as a noun in the sentence, which makes it the gerund.
Thus, the gerund in the sentence is "beginning".