In the inequality \( Bx + 72 < 12 \), the term that is a letter coefficient is:
B. B
In this case, \( B \) is the coefficient of the variable \( x \). The term \( Bx \) as a whole represents a product of the coefficient \( B \) and the variable \( x \), but the specific letter coefficient in this context is the letter \( B \) itself.