Option B: 44
Let's break down the problem step by step:
     ● Total Musicians: 120  
     ● Musicians who can play all three instruments (Guitar, Violin, Flute): 5% of 120 = 0.05 * 120 = 6 musicians  
     ● Musicians who can play any two and only two instruments: 30 musicians  
     ● Musicians who can play the guitar alone: 40 musicians  
     We need to find the total number of musicians who can play the violin alone or the flute alone.
     Let's denote:
         ○ \( G \) as the set of musicians who can play the guitar
         ○ \( V \) as the set of musicians who can play the violin
         ○ \( F \) as the set of musicians who can play the flute
     From the given information:
         ○ \( |G \cap V \cap F| = 6 \) (musicians who can play all three instruments)
         ○ \( |G \cap V| + |V \cap F| + |F \cap G| = 30 \) (musicians who can play any two and only two instruments)
         ○ \( |G| - |G \cap V| - |G \cap F| + |G \cap V \cap F| = 40 \) (musicians who can play the guitar alone)
     We need to find \( |V| - |G \cap V| - |V \cap F| + |G \cap V \cap F| \) (musicians who can play the violin alone) and \( |F| - |F \cap G| - |F \cap V| + |G \cap V \cap F| \) (musicians who can play the flute alone).
     Using the principle of inclusion-exclusion for three sets, we have:
     \[
     |G \cup V \cup F| = |G| + |V| + |F| - |G \cap V| - |V \cap F| - |F \cap G| + |G \cap V \cap F|
     \]
     Since \( |G \cup V \cup F| = 120 \), we can substitute the known values:
     \[
     120 = 40 + |V| + |F| - 30 + 6
     \]
     \[
     120 = 46 + |V| + |F| - 30
     \]
     \[
     120 = 16 + |V| + |F|
     \]
     \[
     |V| + |F| = 104
     \]
     Now, we need to find the number of musicians who can play the violin alone or the flute alone:
     \[
     |V| - |G \cap V| - |V \cap F| + |G \cap V \cap F| + |F| - |F \cap G| - |F \cap V| + |G \cap V \cap F|
     \]
     Since \( |G \cap V| + |V \cap F| + |F \cap G| = 30 \) and \( |G \cap V \cap F| = 6 \), we can simplify:
     \[
     |V| + |F| - 2 \times 30 + 2 \times 6 = 104 - 60 + 12 = 56
     \]
     Therefore, the total number of musicians who can play the violin alone or the flute alone is:
     \[
     104 - 56 = 48
     \]
     However, we need to account for the overlap of those who play two instruments, which was already considered in the 30 musicians who play any two instruments. Thus, the correct calculation should be:
     \[
     |V| + |F| - 30 = 104 - 30 = 74
     \]
     But since we need to find those who play only one instrument, we subtract the overlap:
     \[
     74 - 30 = 44
     \]
     Therefore, the total number of musicians who can play the violin alone or the flute alone is 44.