The correct options are
A x−y+3=0
D 3x−y+1=0
Parabola equation : y2=12x
⇒a=3
Equation of tangent in slope form is
y=mx+am
⇒ y=mx+3m
This equation passes through (1,4)
⇒4=m+3m
⇒4m=m2+3
⇒m2−4m+3=0
⇒m2−3m−m+3=0
⇒m(m−3)−1(m−3)=0
⇒(m−1)(m−3)=0
So, m=1,3
Equation of tangent :y=x+31
⇒x−y+3=0
For m=3, y=3x+33
⇒3x−y+1=0