Answer:
The type of ink used for printing changed from water-based to oil-based.
Step-by-step explanation:
The point that is not relevant, or necessary, to support the author's claim about the effects of the printing press is that "The type of ink used for printing changed from water-based to oil-based."
This particular option did not express the importance or effect of the printing press. The effect of the printing press actually means what impact the printing press is making in various areas of human life.
Definitely, Option C is not relevant or necessary to support the author's claim.