Grapevine fan leaf disease caused by virus is transmitted by -

Correct option is A

· Correct answer: (a) Xiphinema
· Xiphinema is a nematode that acts as a vector for the grapevine fan leaf virus, which causes a significant decline in grape production.
Other options:
· (b) Trichodorus: A genus of nematodes but not involved in transmitting this virus.
· (c) Paratrichodorus: Another nematode but not responsible for this specific disease transmission.
· (d) Ralstonia: A bacterial pathogen, not related to grapevine fan leaf virus.