What does Old Musoni mean when he says to his son, "…where do you think you are going, a mere beardless kid with the milk not yet dry on your baby nose?"

He meant that his son was still very young and did not have the experience and ability to face the responsibility he wanted.

Explanation:

In the sentence above, Old Musoni states that his son is inexperienced and has not learned with his life the skills necessary to carry certain responsibilities, as these skills are learned over the years, with the mentality of an adult and the development of the human being. Your son didn't learn any of that, because he hasn't lived yet. He is too young, a child to understand the reality and the difficulty of things.

i believe the answer is a

the steam engine.

the locomotive.

the telephone.

the telegraph.

the internal combustion engine.

the rifle.

ironclad ships.

electricity/light bulb.