As we know that electric flux is given by
![\phi = E.A](https://img.qammunity.org/2020/formulas/physics/high-school/6x13plk640ymt95oqo5t5tceek3bjz6f2g.png)
![\phi = EAcos\theta](https://img.qammunity.org/2020/formulas/physics/high-school/dl4bhd2onsb5lwlw6ouuxo9vmnizxwu1hs.png)
so in order to increase the flux we have two options
1. By increasing the area of the disc
2. by changing the orientation of disc so the area of the disc is parallel to the electric field
so correct answer will be
A. increasing the area of the disk