The measure of an acute angle is any angle that is less than 90 degrees.
Out of the given options:
A. 126° - This is an obtuse angle because it is greater than 90 degrees.
B. 86° - This is the correct answer as it is less than 90 degrees, making it an acute angle.
C. 90° - This is a right angle, not an acute angle, because it exactly measures 90 degrees.
