To find the ninth term \( a_9 \) of the arithmetic sequence given by the formula \( a_n = 3.7 + 12n \), we need to substitute \( n = 9 \) into the formula.
\[ a_9 = 3.7 + 12 \cdot 9 \]
Now, calculate \( 12 \cdot 9 \):
\[ 12 \cdot 9 = 108 \]
Now substitute this back into the formula:
\[ a_9 = 3.7 + 108 = 111.7 \]
Now let's round \( 111.7 \) to the nearest tenth, although it is already rounded.
Thus, the ninth term \( a_9 \) is:
\[ \boxed{111.7} \]
Please note that none of the provided responses were correct since \( a_9 \) calculates to \( 111.7 \), which is not among the provided options.