No parking signs indicate:

Answer: B — That parking is prohibited at all times

No parking signs are designed to clearly communicate that parking is prohibited at all times in the designated area. These signs serve a critical function in maintaining safety and flow of traffic, allowing for emergency access, street cleaning, and preventing obstruction in areas where vehicles should not be left unattended. In regions where these signs are posted, it is important for drivers to comply strictly to avoid fines or accidents. The other choices suggest parking is permissible under certain conditions, but this contradicts the primary purpose of a "No Parking" sign. Therefore, the selection accurately reflects a situation where parking is entirely prohibited, reinforcing proper adherence to traffic regulations.