Which of the following is a parasitic alga on tea or coffee plants?

The correct option is A Cephaleuros
Cephaleuros is a genus of parasitic thalloid green algae which is commonly called red rust. It is parasitic on some important economic plants of the tropics and subtropics such as tea, coffee, mango and guava causing damage limited to the area of algal growth on leaves (algal leaf spot), or killing new shoots or disfiguring fruits.