there shall be excluded any gain or loss—

(A) which is considered as gain or loss from the sale or exchange of a capital asset,

(B) from the cutting of timber, or the disposal of timber, coal, or iron ore, if section 631 applies to such gain or loss, or

(C) from the sale, exchange, involuntary conversion, or other disposition of property if such property is neither— (i) stock in trade or other property of a kind which would properly be includible in inventory if on hand at the close of the taxable year, nor (ii) property held primarily for sale to customers in the ordinary course of the trade or business;