Read the following passage carefully:
Long before Dr. Hélène Laurent published her definitive analysis of Lake Vostok sediment cores in 2018, her research team faced years of technical and logistical challenges. In 2005, initial seismic surveys revealed a thermal anomaly beneath the East Antarctic ice sheet, prompting an international consortium to authorize exploratory drilling. However, physical core extraction did not commence until five years later, following two years devoted entirely to engineering specialized hot-water drills. In mid-2014, while preliminary geochemical scanning was underway in her Geneva laboratory, Laurent unearthed an uncataloged 1999 survey log from an earlier Soviet expedition. This archival discovery prompted her to re-evaluate the sediment depth calculations she had presented at the Oslo Climatology Symposium just two months prior to finding the log. Re-analyzing the core samples with calibrated isotopic sensors in late 2015 finally confirmed pre-glacial organic markers, supplying the crucial evidence needed for her eventual publication.
According to the passage, which of the following events occurred FIRST chronologically?
- The compilation of a survey log during a Soviet expeditionCevap
- BThe authorization of exploratory drilling by the international consortium
- CThe commencement of physical sediment core extraction
- DThe presentation of sediment depth calculations at the Oslo Climatology Symposium