The word that is different in each set is:
long, curly, straight, sim - The word "sim" is different.
hair, height, beard, moustache - The word "height" is different.
stupid, lazy, uniond, generous - The word "uniond" is different.
kind, behind, above, between - The word "kind" is different.
boots, trainers, jeans, sandals - The word "jeans" is different.
bracelet, earrings, tights, necklace - The word "tights" is different.
Regarding the article:
a. а b. в c. с
I hope this helps with your practice! Let me know if you have any more questions. Keep up the excellent work!