Article 69 of the Patent Law shall not be regarded as infringement of the patent right under any of the following circumstances:
(2) Having manufactured the same product, used the same method or made necessary preparations for its manufacture and use before the patent application date, and continuing to manufacture and use it only within the original scope;
Article 69 of the law requires that it can only continue to be manufactured within the original scope, and it is illegal to license others to implement it; Therefore, C infringes.
Article 1 1 of the law.
After the patent right for invention and utility model is granted, except as otherwise provided in this Law, no unit or individual may exploit the patent without the permission of the patentee, that is, it may not manufacture, use, promise to sell, sell or import the patented product for production and business purposes, nor may it use the patented method and use, promise to sell, sell or import the product directly obtained according to the patented method.
D only applied for a patent, but did not manufacture, use, promise to sell, sell or import its patented products for profit, so it is not infringing;
D the patent applied for belongs to related patents, and its production and sales are mutually restricted.