In the equation x(t) = a(t)cos[2πFct+θ(t) ], Which of the following relations between a(t) and x(t), θ(t) and x(t) are true?$

• A. a(t), ‚âà√≠‚Äö√†√®(t) are called the Phases of x(t)
• B. a(t) is the Phase of x(t), ‚âà√≠‚Äö√†√®(t) is called the Envelope of x(t)
• C. a(t) is the Envelope of x(t), ‚âà√≠‚Äö√†√®(t) is called the Phase of x(t)
• D. None of the mentioned