“Obstreperous” means noisy and difficult to control.
Option C is the correct answer because “unruly” means disorderly and not amenable to discipline or control.Hence it is correct because unruly is the correct meaning of the given word in italics.
Option A is incorrect because “awkward” means being uncomfortable about soemthing, which is not related here, hence incorrect.
Option B is incorrect because “lazy” means not willing to work or use energy, which is incorrect for the given word.
Option D is incorrect because “sullen” means bad tempered and sulky which doesn’t necessarily mean that cannot be controlled, hence it is incorrect.