In the following question, a sentence has been given in Active/Passive voice. Out of the four alternatives suggested, select the one which best expresses the same sentence in Passive/Active voice. The moist air will corrode the beam.

• Corroding of the beam will be done by the moist air.
• Corrosion of the beam by the moist air would be done.
• The beam would be under corrosion by moist air.
• The beam will be corroded by moist air.