A noun is required after the possessive adjective ‘its’. ‘Infancy’ (from infant) refers to the early stage of development or existence of the profession.
A noun is needed here. ‘Insight’ (from see) means a deep understanding of a person or thing, or a clear perception of its nature.
The (3)
A noun is required to serve as the subject of the sentence. ‘Commitment’ (from commit) refers to the state of being dedicated to a specific cause or activity.
A noun is needed to describe the ‘feelings’. ‘Loneliness’ (from lonely) refers to the sadness caused by being alone or lacking contact with others.
An adverb is needed to modify the phrase ‘the most effective way’. ‘Undeniably’ (from deny) means in a manner that cannot be disputed or questioned.