Answer:
B. There is an increase in income and "spring shoes" are a normal good.
Explanation:
To eliminate the disequilibrium in the market for shoes, spring shoes firstly needs to be seen as a normal product because if it is seen an inferior product then as people's Income rises they woudnt want to buy inferior products because they have the income to buy normal products. As people income rises, since spring shoes is seen as a normal product, then people will buy springshoes