Which one of the following is not a mode of Talaq ?

Talaq-ul-sunnat (the approved forms, ahsan and hasan) and talaq-ul-biddat (the irregular triple form) are modes of talaq, and ila, a husband's vow to abstain from intercourse for four months, is a form of constructive talaq.

Refusal of maintenance is not a mode of talaq; failure to maintain for two years is a ground on which a wife may seek dissolution by the court under section 2(ii) of the Dissolution of Muslim Marriages Act, 1939. Talaq-ul-biddat by triple pronouncement is now void and an offence under the Muslim Women (Protection of Rights on Marriage) Act, 2019.