Which of the following statements is not true for halogens? (NEET 2019)

Fluorine is the most electronegative element and cannot exhibit any positive oxidation state. Other halogens have d-orbitals and therefore, can expand their octets and show +1 ,+3, +5 and +7 Oxidation states. Thus, option (a) is incorrect. (b) All halogens are strong oxidising agents as they have strong tendency to accept an electron. Thus, option (b) is correct. (c) All halogens form monobasic oxyacids. Thus, option (c) is also correct. (d) Electron gain enthalpy of halogens became less negative down the group. However, the negative electron gain enthalpy of fluorine is less than chlorine due