The equation of the tangent to the curve y = x + 4/x², that is parallel to the x-axis, is

y = x + 4x⁻² ⇒ dy/dx = 1 - 8x⁻³
Since, tangent is parallel to x-axis i.e. dy/dx = 0
0 = 1 - 8x⁻³
8x⁻³ = 1
x³ = 8 ⇒ x = 2
Substitute in the equation of the curve
y = 2 + 4/2² = 2 + 4/4 = 2 + 1 ⇒ y = 3.
Equation of tangent is given as y - y₁ = m(x - x₁)[slope-point form]
⇒ y - 3 = 0(x - 2)
⇒ y - 3 = 0
⇒ y = 3
Hence, option 'C' is correct.