Answer:
2. RS=RS
Reason : Reflexive property of equality.
Explanation:
Given RT=RU
TS=US
To prove that

Proof:
1. Statement: RT=RU; TS= US
Reason: Given in question
2.Statement: RS=RS
Reason: Reflexive property of equality.
Reflexive property: It is that property of equality which define a relation with itself.
3. Statement:

Reason: SSS ( Side -SIde -Side congruence property of triangles)
Hence proved.
The correct answer is reflexive property of equality .