Step 1: Match the Pairs:
A. Scrapie: A fatal degenerative disease affecting the nervous system of Sheep and goats. It is caused by Prions.
Match: A - IV.
B. Vein clearing: A common symptom of viral infection in plants, notably Bhendi (Yellow Vein Mosaic of Okra).
Match: B - III.
C. Malformation: Cocoa Swollen Shoot Virus causes swelling and malformation. (Also Mango malformation exists, but Cocoa is the remaining option suitable for 'malformation' or swelling symptoms in this set).
Match: C - II.
D. Breaking of flowers: Refers to the "breaking" (streaking) of flower color, famously caused by the Tulip Breaking Virus in Tulip.
Match: D - I.
Step 2: Conclusion:
The correct matching sequence is A-IV, B-III, C-II, D-I. This corresponds to Option (C).