(a) Academic probation. A student who has attempted at least 12 semester or 18 quarter units as shown by the official academic record shall be placed on academic probation if the student has earned a grade point average below 2.0 in all units which were graded on the basis of the grading system described in section 55023.

(b) Progress probation. A student who has enrolled in a total of at least 12 semester or 18 quarter units as shown by the official academic record shall be placed on progress probation when the student receives symbols of “W,” “I,” or “NP” (as defined in sections 55023 and 55030) in fifty percent (50 percent) or more of all units in which a student has enrolled.

(c) The governing board of a community college district may adopt standards for probation, provided any such standard is at least as favorable to student progress as the standards established in subdivisions (a) and (b).