Right choice is (d) Use of clean steel instead of rimmed steel, applying metallic, inorganic and organic coatings and use of nickel-based alloys
Easiest explanation: Preventions of hydrogen blistering are:
Use of clean steel instead of rimmed steel
Applying metallic, inorganic and organic coatings
Use of substituting alloys such as nickel-based alloys
Removing poisons such as sulfides, arsenic compounds, cyanides, and phosphorus ions.