Passage Summary: Front-loading washers don't use much water, which means normal powder soap doesn't melt right, so you have to use special soap if you want clean clothes.

Conclusion: To achieve truly clean laundry in a front-loading machine, one must use specialized detergent rather than standard powder.

Reasoning: Front-loading machines use less water, which prevents standard powder detergent from dissolving easily.

Analysis: The argument assumes that if a detergent doesn't dissolve 'readily,' it cannot get clothes 'really clean.' There is a logical gap between the physical state of the soap (dissolving) and the final result (cleanliness). To find the necessary assumption, ask yourself: 'If powder detergent could still clean clothes well even without dissolving perfectly, would this argument fall apart?' The answer must connect the lack of dissolving to the failure to clean.