Which of the following is correct about viroids?

Banana bunchy top is caused by

The figure given below shows the structure of a bacteriophage. Identify its parts labelled as $A, B, C$ and $D$.

Lichen is usually cited as an example of 'symbiosis' in plants where an algal and a fungal species live together for their mutual benefit. Which of the following will happen if algal and fungal partners are separated from each other?
$A$. Both will survive and grow normally and independent from each other.
$B$. Both will die.
$C$. Algal component will survive while the fungal component will die.
$D$. Fungal component will survive while algal partner will die.
Based on your answer,how do you justify this association as symbiosis?

Which of the following acts as a pollution indicator?

Lichens do not like to grow in cities.