Answer:
The answer is True.
Step-by-step explanation:
The word arbitrary means something that is based on or determined by individual preference or convenience rather than by necessity or the intrinsic nature of something.
Therefore, the word submarine in the question above serve the purpose of arbitrariness for both Joseph and Alphonse. This means that each of them is free to interpret the word whichever way they like, and this must not necessarily be related, it just has to serve their personal bias.