Blossom end rot disorder in tomato has been found to be caused by the deficiency of

Answer: Option B

Blossom end rot disorder in tomato is caused by the deficiency of Ca.
Blossom end rot is caused by a localized calcium deficiency in the distal end of the fruit.
Calcium is a relatively immobile element; calcium uptake is therefore heavily influenced by anything that affects water uptake by a plant.
It is required in relatively large quantities by rapidly growing fruit, especially by those cells at the blossom end of the young fruit.