Under the provisions of ASC 805-30, in a business combination, when the investment cost exceeds the total fair value of identifiable net assets acquired, which of the following statements is correct?

a. The difference is allocated first to reduce proportionately (according to market value) non-current assets, and any negative remainder is classified as an extraordinary gain.

b. The excess is first assigned to identifiable net assets according to their fair values; then the rest is assigned to goodwill.

c. The difference is allocated first to reduce proportionately (according to market value) non-current, depreciable assets to zero, and any negative remainder is classified as a deferred credit.

d. The difference is allocated first to reduce proportionately (according to market value) non-current assets, then to non-monetary current assets, and any negative remainder is classified as a deferred credit.