The statement "in presenza del segnale raffigurato si deve usare prudenza nella strettoia perché la circolazione si svolge a doppio senso" translates to "in the presence of the depicted sign, caution must be used in the narrow passage because traffic is two-way." Based on official Italian driving quiz and road sign explanations, this statement is actually false. The sign in question is a warning sign indicating that a one-way road segment is ending and two-way traffic is beginning, so caution is warranted. However, the key point is that the sign does not indicate a narrow passage or mean the traffic flow is strictly two-way within a narrow passage needing extra prudence. It mainly signals the transition from one-way to two-way traffic, requiring drivers to be cautious but not specifically due to a "strettoia" (narrow passage) with two-way traffic.

Therefore, the correct understanding is: This sign indicates that the one-way circulation ends and two-way traffic begins, so drivers should be cautious due to encountering opposing vehicles, but the caution is not specifically because of a narrow passage with two-way traffic. The circulation becoming two-way is a warning to exercise prudence, not a sign of a narrow two-way road segment alone. This clarifies that the original phrase is often marked as false in official quizzes, emphasizing the transitional nature of the sign rather than strict narrow two-way circulation.