The following sentence has been divided into four segments. Identify the segment that has a grammatical error.
Soldiers in / the Indian Armed Forces are / trained never to / fight cowardly.

The correct segment containing the grammatical error is "trained never to".

Step-by-step Explanation:
1. Analyze the Sentence Structure: The given sentence is: "Soldiers in the Indian Armed Forces are trained never to fight cowardly."
2. Identify the Grammatical Issue: In standard English grammar, the position of the adverb "never" in relation to the infinitive "to fight" is key. Placing the adverb "never" before the particle "to" (as in "never to") can create an awkward or incorrect modifier placement in this context. The more standard and grammatically accepted placement is to position the adverb either after the infinitive marker "to" (forming a split infinitive: "to never fight") or to rephrase the sentence to ensure smooth flow (e.g., "trained not to fight cowardly").
3. Conclusion: Based on these grammatical rules, the segment "trained never to" is identified as containing the grammatical error.