Winkler owns a four$-$unit townhouse building that he rents to tenants. He just purchased it with a $$100,000$ down payment and a $$600,000$ mortgage from Porcine Bank. The replacement cost value of the entire building, exclusive of land, is $$800,000.$ Apart from any use value, who has an insurable interest in the building itself, and to what extent?

$($Search Chapter $2)$

a$.$ Winkler and Porcine both have an $$800,000$ insurable interest.

b$.$ Winkler has a $$100,000$ insurable interest, and Porcine has a $$600,000$ insurable interest.

c$.$ Winkler has a $$700,000$ insurable interest, and Porcine has a $$600,000$ insurable interest.

d$.$ Winkler has an $$800,000$ insurable interest, and Porcine has a $$600,000$ insurable interest