Which of the following describes a gaining stream?

A gaining stream is characterized by its ability to receive water from the groundwater. This occurs when the water table is higher than the streambed, allowing water to flow into the stream, thus increasing its flow. The flow of water from the groundwater to the stream helps to maintain the stream's flow levels, especially during drier periods.

In contrast, a stream that dries up in summer typically indicates a losing stream, where surface water is lost to the groundwater system, diminishing its flow. A stream running parallel to rivers does not play a role in the definition of gaining or losing characteristics. Finally, the depth of the stream being too shallow for fish is not related to the processes of gaining or losing water but rather pertains to the stream's habitat and ecological factors.