Final answer:
Hilda should aim for a concept-based magazine cover typically seen in independent magazines, which allows for a creative blend of visuals and text to communicate the message of saving water.
Step-by-step explanation:
Hilda should create a concept-based magazine cover. This type of magazine cover is often found in independent magazines. A concept-based cover allows for a thematic presentation combining illustration, text, and image; this is essential to communicate complex ideas such as saving water in a powerful and visually engaging way. Independent magazines frequently use such covers to convey in-depth and thought-provoking messages on various social causes.