The correct option is C Pair of straight lines
Given equation is 16x4−y2=0
⇒(4x2−y2)(4x2+y2)=0
⇒(2x−y)(2x+y)(4x2+y2)=0
Since both x and y are real, hence
4x2+y2=0 can only be zero, if (x,y)=0.
Thus 4x2+y2=0 represents a point.
And (2x−y)(2x+y)=0 ⇒2x−y=0 or 2x+y=0.
Thus, it represents a pair of straight lines.