On January $2$ of the current year, Black acquired a $50\%$ interest in New Partnership by contributing property with an adjusted basis of $$7,000$ and a fair market value of $$9,000,$ subject to a mortgage of $$3,000.$ What was Black's basis in New Partnership at January $2$ of the current year?

a$.$ $$3,500$

b$.$ $$4,000$

c$.$ $$5,500$

d$.$ $$7,500$