Which one of the following is correct expression. Where t is torque, B magnetic field, M is the moment

• A. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/200-311-1.png">
• B. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/200-311-2.png">
• C. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/200-311-3.png">
• D. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/200-311-4.png">