Correct Answer:
B. serious
Explanation:
The correct answer is serious because the surrounding context implies a focused, determined effort aimed at successfully achieving a resolution.
- Step 1 (Collocation and Context): While other modifiers can describe an 'attempt' grammatically, pairing it with 'to solve the problem' logically highlights a purposeful and earnest commitment to finding a fix.
- Step 2 (Application): A 'serious attempt' is a standard English collocation that denotes an individual used genuine effort and thought to crack a difficult task.
- Incorrect Options:
- weak is incorrect because a half-hearted or superficial effort is unlikely to resolve a structural issue.
- lazy is incorrect because a lazy disposition directly undermines the active execution needed to address a problem.
- careless is incorrect because working without proper attention or accuracy generally introduces errors rather than solving problems.