Choose the option that best completes the sentence. These properties were ____ sale before the fire gutted them.

To understand which option best completes the sentence, let's examine the meaning of each phrase:

• Up for sale: This means that something is available to be sold. The phrase "up for" indicates that the properties were being offered to potential buyers before any incident happened.
• Up on: This phrase is generally used to indicate being current with information or being knowledgeable about something. It is not typically used with "sale."
• Out for: This phrase usually suggests looking for or aiming to achieve something. It doesn't fit well in the context of items being sold.
• Down on: This implies having a negative attitude towards someone or something. It doesn't relate to the context of selling properties.

Given these meanings, the phrase that best completes the sentence is "up for sale." Therefore, the sentence should read: "These properties were up for sale before the fire gutted them."