@SMickey,
A. 'Makguksu' is a kind of noodle.
correct
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B. Makguksu means noodle that crumbled and eaten carelessly, which is made from buckwheat.
Well, I believe a verb is missing between 'that' and 'crumbled'.
b. Makguksu means noodle that IS crumbed and eaten carelessly, which is made from buckwheat.
the whole sentence needs work
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c. This is similar TO Ramyun, but the noodle is better cut and its texture is softer.
note the edit
alternatively : This is similar to Ramyn but the noodle is better cut and has a softer texture.
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D. I think it is the most delicious.
The article 'the' lets you expect to see a noun later,
so you should either add a noun or cross out 'the'.
d1. I think it is most delicious. OR
d2. I think it is the most delicious food.
needs context