Which Of the above Spread Plant Diseases?

Consider the following:

1. Birds
2. Dust blowing
3. Rain
4. Wind blowing

Which of the above spread plant diseases?(2018)

a) 1 and 3 only

b) 3 and 4 only

c) 1, 2 and 4 only

d) 1, 2, 3 and 4

Answer: D