The correct option is C 300 units
Given,
Electric field vector, →E=8^i+4^j+3^k
As , the plane surface is parallel to x-yplane, so the area vector →A points along the positive direction of z-axis.
So, area vector, →A=100^k
Electric flux through the surface,
ϕ=→E.→A
⇒ϕ=(8^i+4^j+3^k).(100^k)
∴ϕ=300 units
Hence, option (b) is the correct answer.