Given the task definition and input, reply with output. In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to evolve porygon [title] Obtain an up-grade. [step] You will need to give this item to porygon to hold. When porygon is traded while holding an up-grade, it will evolve into porygon2. <sep> (A) All you'll need to sell porygon2 is the final cure for ugali. [substeps] Poisson's final cure is 5 , 000 gold; this way, porygon2 will unlock your poisson's maximum cure by dropping 100 gold. (B) You can trade it for one high-grade tablet, or the combination of various previously traded tablets. This is pretty heavy trading as some tablets are sold for much less than others, requiring much more money. (C) This is the non-optimal type of porygon2 you will need to get. [substeps] You will need to trade porygon2 for an up-grade. (D) You can get an up-grade in gen 2 (gold, silver, crystal) and later. [title] Equip porygon with the up-grade item.
D