Former game show host Bob Barker contributed a building with an adjusted basis to Bob of $$50,000$ and a fair market value of $$150,000$ subject to a mortgage of $$120,000$ in exchange for a $30$ percent interest in the Come$-$on$-$down Partnership. Alpha will assume the mortgage on the building. What is the Come$-$on$-$down Partnership's basis in the building?

a$.$ $$0$

b$.$ $$30,000$

c$.$ $$50,000$

d$.$ $$84,000$