John Smith purchased real estate for $40,000 using separate property funds. Although he provided the entire purchase price, John titled the property in his and his spouse Laura's name as joint tenants with the right of survivorship. John died in the current year when the property was valued at $90,000. What amount is included in John's estate?

A. 0 B. $90,000 C. $45,000 D. None of the above