The answer is: B
Explanation
The correct option is B: The onus of proving the grave and sudden provocation is on A.
According to the principle given, the burden of proof lies on the accused who seeks to bring her case under any of the general exceptions or special exceptions or provisos in the Indian Penal Code or any other law. Therefore, A has to prove that she committed the murder under grave and sudden provocation, which is a general exception under Section 300 of the Indian Penal Code. The court will presume that A did not act under grave and sudden provocation unless she proves otherwise.
Option A is incorrect because A's statement is not an admissible confession. A confession is an admission of guilt, whereas A is claiming a defence of grave and sudden provocation. Moreover, a confession made in a court of law is not conclusive proof of guilt and can be rebutted by other evidence.
Option C is incorrect because the onus of disproving the grave and sudden provocation is not on the prosecution. The prosecution only has to prove the essential ingredients of murder, such as intention, knowledge, or cause of death. The prosecution does not have to disprove the defence taken by the accused unless there is some evidence to support it.
Option D is incorrect because the onus of proving the grave and sudden provocation is not on the prosecution. As explained above, the prosecution does not have to disprove the defence taken by the accused unless there is some evidence to support it.
Option E is incorrect because the court will not presume that A's statement is the truth in the absence of conflicting circumstances. The court will presume the absence of grave and sudden provocation unless A proves it. A's statement alone is not sufficient to establish her defence and she has to produce other evidence to corroborate it.