Yes! Paragraph's (b) and (d) are paired to each other.  

If your schedule changes regularly within a month, like from day shifts to night shifts, or 0700 this time and 0800 another, then you cannot use (c).

(c) is not a duty time limitation of 14 hours.   It's just saying that if a pilot's schedule can't be held within a regurlarly assigned duty 14 hour schedule,  you cannot take advantage of the flight time benefits of (c), and must use (b)/(d).

There is no 14 hour duty time limitation in Part 135