Solution

If every requirement stated in the Software Requirement Specification (SRS) has only one interpretation, then SRS is said to be Unambiguous.

Therefore the correct answer is option 3.

Points to note: 

SRS (Software Requirement Specification) is written by either customer or developer. It Serves as a contract between customer and developer.

  Following are the characteristics of a good SRS :

• Correct :- Every requirement stated therein the SRS is one that software shall meet.
• Unambiguous :- Every requirement stated therein the SRS has only one interpretation.
• Complete
• Consistent :- Subset of individual requirements described in SRS should not conflict.
• Verifiable :- Requirements must be verified.
• Modifiable :- Requirements specified in the document are changeable.
• Traceable :- Further enhancements are possible.