According to API RP 941 and API RP 571, High Temperature Hydrogen Attack (HTHA) is highly influenced by hydrogen partial pressure at elevated temperatures:
"The likelihood and rate of HTHA increase with both temperature and hydrogen partial pressure. Operating beyond established material limits on the Nelson Curves can lead to internal decarburization and methane formation in the steel." (Reference: API RP 571, Section 4.2.1.3 - High Temperature Hydrogen Attack) Therefore, among all listed damage types, HTHA is the most directly affected by high hydrogen partial pressures, making option D correct.