For transformation, micro-particles coated with DNA to be bombarded with biolistic gene gun are made up of?

The correct option is B Gold or tungsten
A gene gun is a system in which a particle is used to inject the genetic material directly into the host's genome. This method is known as biolistic particle delivery system which was originally designed for plant transformation. A metal particle is coated with the genetic material and transferred into the host cells to allow the foreign DNA get incorporated into the hosts' genome. The particles are generally made up of the inert materials like the gold or tungsten which are inert and does not react with the DNA. The particles are accelerated with force to enter into the cells and then the selectable markers are used to identify the cells that take up the transgene.

Thus, the correct answer is option B.