Louis Always Knits Ten Sweaters a Year to Give as Birthday

Louis always knits ten sweaters a year to give as birthday gifts to his nephews.One year,instead of giving the sweaters as gifts,he sells them to a local store for $50 each; his nephews receive no gifts.What is the effect on GDP?

A) GDP increases
B) GDP decreases
C) there is no change in GDP
D) GDP increases only if the $50 sweaters are comparable to store-bought sweaters
E) GDP increases only if the $50 price is less than the cost of materials