To determine the direction of heat flow between the two solid blocks, we need to consider their temperatures. Heat flows from the block at a higher temperature to the block at a lower temperature.
If Block A is at a higher temperature than Block B, heat will flow from Block A to Block B.
If Block B is at a higher temperature than Block A, heat will flow from Block B to Block A.
Without specific temperatures given, I can't provide a definitive answer or select a diagram. However, you should choose the diagram that indicates heat flowing from the hotter block to the cooler block based on the temperature information you have.