Concept: The sentence needs a word that expresses correcting a wrong or making amends for a complaint.
Explanation: "Redress" means to remedy, set right, or make amends for an injustice or grievance.
This directly matches the intended meaning of putting a wrong situation right.
"Litigation" refers only to the formal process of taking legal action in a court of law.
This word merely describes legal procedure and does not carry the meaning of correcting a wrong.
"Address" can mean to speak to someone or to deal with a matter, but it does not strongly imply making amends.
"Restoration" means returning something to its former condition, which is a different idea from remedying an injustice.
Among the four options, only "redress" gives the precise meaning needed to complete the sentence.
Answer: A. redress