The correct option is
A specialised parenchymatous cells which contain ergastic substances
An idioblast is an isolated plant cell that differs from neighboring tissues. They have various functions such as storage of reserves, excretory materials, pigments, and minerals. They could contain oil, latex, gum, resin, tannin or pigments etc. Some can contain mineral crystals such as acrid tasting and poisonous calcium oxalate or carbonate or silica.
So, the correct answer is 'specialised parenchymatous cells which contain ergastic substances'