Concept: A dying declaration is a statement made by a person as to the cause of his death or circumstances of the transaction resulting in his death.
Step 1: Understand evidentiary value of dying declaration.
Dying declaration is relevant because the law assumes that a person near death is unlikely to lie.
\[
\text{Dying declaration} \Rightarrow \text{Relevant evidence}
\]
Step 2: Understand the rule of reliability.
If a dying declaration is found truthful, voluntary and reliable, it may form the sole basis of conviction.
\[
\text{Reliable dying declaration} \Rightarrow \text{Can support conviction}
\]
Step 3: Identify the case.
The Supreme Court laid down this principle in Khushal Rao v. State of Bombay.
Therefore, the correct answer is Khushal Rao v. State of Bombay.