Correct Answer:
B. My father advised me not to ride in the rain.
When transforming a negative imperative command (starting with "Do not...") from direct to indirect speech, specific structural adjustments must occur.
- The reporting verb "said to" transitions into a verb that reflects the tone of the utterance, which is why advised is used.
- The negative imperative shifts into a negative infinitive pattern: not to + verb. This makes "My father advised me not to ride in the rain" the only grammatically valid transformation.