Registration fees usually range from _______ to _______.  

A. $50; $100
B. $15; $50 
C. $45; $90 
D. $25; $75 

 B.

To determine the correct answer, we need to analyze the given options and identify the range of registration fees.

Option A states that registration fees range from $50 to $100. This means that the lowest fee is $50 and the highest fee is $100. However, this range does not match the given question, which asks for the usual range of fees.

Option B states that registration fees range from $15 to $50. This range matches the question, as it provides a lower and upper limit for the usual registration fees. Therefore, option B is a plausible answer so far.

Option C states that registration fees range from $45 to $90. This range is within the given options, but it does not match the question's requirement of usual fees.

Option D states that registration fees range from $25 to $75. Although this range is within the given options, it does not match the question's requirement of usual fees either.

Therefore, the correct answer is option B, where registration fees usually range from $15 to $50.