"a listing contract under which the broker's commission is contingent upon his producing a ready, willing, and able buyer before the property is sold by the seller or another broker is known as: "

Open listing agreement

Explanation:

Open listing agreement - it is type of listing in which buyer sold the property by themselves rather than by broker hence broker commission is dependent upon his willingness before the property.

In this listing, owner can list different broker for the property and only pay to the broker who will bring potential customer and that selected by owner.

in about winter like late november to january

the answer is d.index