What is the condition to achieve oscillations?

• A. |A‚Äö√†√∂‚àö¬∫|=1
• B. ‚Äö√Ñ√∂‚àö‚Ć‚Äö√тĆA‚Äö√†√∂‚àö¬∫=0^o
• C. ‚Äö√Ñ√∂‚àö‚Ć‚Äö√тĆA‚Äö√†√∂‚àö¬∫=multiples of 2‚âà√¨‚àö√ë
• D. All the mentioned