Any asset acquired or disposed of by a person chargeable to tax shall, be deemed to have been acquired or disposed of at the date at which there is an enforceable right to acquire or a binding duty to dispose of the asset or any right or interest in it, and in particular, where —
(a)
any contract is to be performed subject to any condition, the date of acquisition or disposal of the asset shall be the date the condition is satisfied ;
(b)
consideration under the contract does not depend solely or mainly on the value of the asset at the time the condition is satisfied, the acquisition or disposal shall be treated as if the contract had never been conditional, in which case the date of the acquisition or disposal of the asset shall be the date of the contract ; or
(c)
an option is conferred by virtue of any contract, the date of the acquisition or disposal of the asset shall be the date when the option is exercised.