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, and his nephews receive no gifts.What is the effect on GDP?  

A)  GDP increases. 
B)  GDP decreases. 
C)  GDP does not change. 
D)  GDP increases only if the $50 sweaters are comparable to store-bought sweaters.