Correct option is C
• The sentence expresses strong obligation or necessity.
• “Must” is used when something is compulsory or very important.
• Here, keeping sharp equipment away from kids is a safety requirement, so “must” is appropriate.
• Correct sentence: Sharp equipments must be kept away from kids.
Meanings of other options:
• may – shows permission or possibility
• shall – used for future or formal obligation
• would – used for past habit or polite request