1. (a) The reasonable value thereof on December 31.
2. (b) The cost of acquisition, increased by so much of the book profit if any, involved in the sale price, as will bear to the total book profit the same proportion that payments received on account of the sale price bear to the total sale price.

3. (c) The unpaid principal of such several contracts of sale without addition of interest in arrears or accrued and without addition of advances made.

   Advances made on such contracts must not be listed elsewhere as assets unless deducted as “Assets Not Admitted.” Interest on such contracts which is in arrears shall not, unless also deducted under “Assets Not Admitted,” be listed elsewhere as an asset; provided, however, if the balance due, including interest, under any contract of sale is less than 66 2/3% of the value of the underlying real estate, then interest which is in arrears on any contract may be admitted as an asset but not in excess of one year's interest.

Real property under contract of sale shall be valued at an amount not in excess of the lowest of the following: