Final answer:
TC 21-305-20 contains 27 chapters, which makes option d) the correct answer.
Step-by-step explanation:
The Army Training Circular (TC) 21-305-20 details training for operations of military vehicles. When you asked how many chapters are in TC 21-305-20, the correct answer is 27 chapters. The information you provided, which includes chapter 17 details and points to items numbered beyond 25, suggests that there are at least 27 items or chapters covered, with chapter 27 being explicitly mentioned. If TC 21-305-20 is associated with a military or technical document, I recommend checking the latest and official version of the document or consulting relevant authorities to obtain the accurate and up-to-date information on the number of chapters it contains.