Romane noticed their display campaign had a high detail page view rate, but low conversion rate. This most likely indicates that:

The selected answer Shoppers are not moving from consideration to conversion is correct because a high detail page view rate combined with a low conversion rate typically indicates that while many shoppers are showing interest in the product by viewing the product detail page, they are not proceeding to make a purchase. This suggests that the shoppers are stuck at the consideration stage of the buyer’s journey, evaluating the product, but are not converting into actual buyers. The issue could be related to factors such as the product's price, value proposition, or competition, which may deter potential customers from completing the purchase despite initial interest. Therefore, the problem lies in the transition from consideration to conversion.