The correct answer to this open question is the following.
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Pebbles cereal could be classified according to the Boston Consulting Group model as a "Problem Child."
When the Boston Consulting Model classifies some product as a "Problem Child" or "Question Mark," this means that the product is high growth markets but low market share. This position has a risk. The product could become a star, which means products in high growth markets with a market share as high as the growth, or, on the other hand, the product could fail and drop to be placed on the "Dog" box, which means that the product has low growth and no market share. This is a very delicate position for the product because the company often invest money that has no further effect.