A.I. Explanation:

Option 1: "He can cut his losses and achieve sustained growth through stocking of safe items."

Explanation: The text states that if a bookseller chooses to sell only safe items to a restricted circle of customers, he cuts himself off from vital aspects of his trade, leading to mediocrity and stagnation. This indicates that stocking safe items does not lead to sustained growth, but rather the opposite.

Option 2: "The safest and most business friendly course for him is to become part of a distribution network."

Explanation: The text suggests that if a bookseller becomes a passive sales representative for large publishing houses or distribution networks, he is no longer a true bookseller. This implies that this course is not the safest or most business-friendly, as it compromises his identity and role.

Option 3: "Speculating about the success of latest publications will be a relatively risk-free preposition."

Explanation: The text describes speculating on the latest publications as a dangerous game, indicating that it is not risk-free. It highlights the constant change in clientele and the potential loss of loyal readers, which contradicts the idea of it being a safe proposition.

Option 4: "He has to walk a tight rope."

Explanation: This option accurately reflects the dilemma faced by the bookseller as described in the text. He must balance the need to stock a variety of books to satisfy public demand while avoiding the pitfalls of unsold inventory, which is akin to walking a tight rope between risk and opportunity.

Option 5: "Reader’s preferences have always to be kept into consideration."

Explanation: The text emphasizes the importance of reader loyalty and the need for booksellers to consider readers' preferences. It states that failing to follow up on a book or author means dismissing the public responsible for their success, highlighting that understanding reader preferences is crucial for a bookseller.