Step 1: Understanding Competency of a Witness:
Under Section 118 of the Indian Evidence Act, 1872, every person is considered competent to testify as a witness if they can understand the questions posed to them and give rational answers. The competency of a witness does not depend on age, sex, or status, but on their mental capacity and ability to comprehend and respond truthfully.
Step 2: Detailed Explanation of the Options:
- (A) Her being intelligent: This alone does not determine competency. Intelligence is not the sole test of competency.
- (B) Must be major: Age is not a criterion for competency; even a child can be a competent witness if they understand the questions.
- (C) Understanding the nature of question: While this is necessary, it must also be coupled with the ability to give rational answers.
- (D) Capable of understanding the nature of question and giving rational answer: This is the correct answer, as per Section 118 of the Evidence Act.
Step 3: Final Conclusion:
The correct answer is (D), as a person who can understand questions and provide rational answers is deemed competent to testify.