💡 Detailed Explanation
The particle '〜さえ' (sae) means 'even...'. It isolates an extreme case (e.g., 'even a child', 'even hiragana') to show that because this extreme level is achieved or failed, all other logical cases are obvious. It directly attaches to nouns, replacing 'が' or 'を'. In negative sentences, it dramatically highlights a severe limitation (e.g., 'cannot even read hiragana'), emphasizing extreme difficulty. In this sentence, it translates perfectly as: "This computer is easy to use even for beginners.". The correct option 'にとっても' dynamically matches the structural requirements and logical flow of the statement. The other options do not satisfy the grammatical construction or fail to convey the appropriate semantic nuance.