The correct sentence is Il n'aime pas la salade, meaning "He does not like salad." This sentence follows the standard French word order and negation pattern correctly.
In French, a basic negative sentence follows the structure: Subject + ne + verb + pas + complement. Breaking down the correct sentence:
Il (subject: he)
n' (ne, elided before the vowel of aime)
aime (verb: likes/loves)
pas (second part of negation)
la salade (complement: the salad)
The other options contain errors:
Elle s'est lave les mains has an agreement error. With reflexive verbs in the passé composé followed by a direct object, the past participle should not agree with the subject. The correct form would be "Elle s'est lavé les mains" (with an accent on the "e" of lavé).
Elle salade n'aime pas has completely jumbled word order. The subject, object, verb, and negation are not in any valid French order.
Il la salade n'aime pas also has incorrect word order. The object "la salade" cannot appear between the subject and the negated verb.
