What is the general equation for elliptic curve systems

• A. y3+b_1 xy+b_2 y=x33+a_1 x2+a_2 x+a_3
• B. y3+b_1 x+b_2 y=x2+a_1 x2+a_2 x+a_3
• C. y2+b_1 xy+b_2 y=x3+a_1 x2+a_2
• D. y2+b_1 xy+b_2 y=x3+a_1 x2+a_2 x+a_3