The correct answer is (d). Austria provided information on the methods used in its NIR. Austria used a Tier 2 method (with country-specific emission factors) to estimate CH4 emissions from cattle (key category) and the Tier 1 IPCC method (with default emission factors) for all other animal species (see also Summary 3 of the CRF). The country-specific emission factors were developed taking into account Austria’s national circumstances. Austria also provided references for its activity data in its NIR and the actual data are reported in Table 4.A of its CRF.