You have to combine like numbers
y-4x-1(1-6x)+3y+x
4y -4x-(1-6x)+x
4y - 4x - 1 + 6x + x
4y + 3x - 1
Cross section of a sphere is a circle
I would say it’s c.
D is wrong cause definitions are proven right all the time.
B is wrong because a definition is not an arrangement of deductions
A is wrong because it says that the statement is not defined when it is.