When can no base, intermediate, or surface mixture be placed concerning the tack coat?

The correct answer highlights the key requirements for the application of mixtures in relation to tack coat procedures. When a tack coat has been applied, it is essential to allow the coating to cure properly before placing any base, intermediate, or surface mixtures. This ensures that the tack coat adheres properly to the layers it is intended to bond with. If the mixtures are placed too soon, the bond between layers may not develop as intended, compromising the overall performance and longevity of the pavement.

The other options suggest scenarios where it might be permissible to place mixtures, but they don't align with standard practices regarding tack application. For instance, waiting for weather conditions like rain or temperature to improve doesn't negate the need for tack coat curing. Similarly, while contractor approval is important in many cases, it does not replace the fundamental principle that proper curing of the tack coat is necessary before subsequent layers are applied.