Which of the following sentences contains both an adverb and a conjunction used correctly in standard English?

Introduction / Context:
Grammar questions in aptitude tests often ask candidates to identify specific parts of speech within full sentences. This question requires recognising both an adverb, which modifies a verb, adjective, or another adverb, and a conjunction, which joins words, phrases, or clauses. Only one of the given sentences contains both elements together in a clear and standard construction.

Given Data / Assumptions:
- We must find a sentence that contains at least one adverb and at least one conjunction.
- The conjunction should link different parts of the sentence (often clauses).
- The adverb should meaningfully modify a verb (for example, describing how an action is done).
- All sentences are grammatically plausible; we focus only on identifying parts of speech.

Concept / Approach:
Common coordinating conjunctions include "and", "but", "or", and "so". Adverbs often end in "-ly" (such as "slowly" or "silently"), though not always. We examine each sentence to see if it contains both a conjunction and a word functioning as an adverb. Mere presence of one of these is not enough; the sentence must have both.

Step-by-Step Solution:
Step 1: Consider option A: "Adam crept silently up the stairs, but could not slow his heartbeat." Step 2: Identify "silently" as an adverb because it describes how Adam crept, modifying the verb "crept". Step 3: Identify "but" as a coordinating conjunction joining two clauses: "Adam crept silently up the stairs" and "could not slow his heartbeat". Step 4: Therefore, option A clearly includes both an adverb and a conjunction. Step 5: Examine option B: "The storm caused flooding as predicted." The word "as" functions more like a subordinating conjunction, and there is no clear separate adverb modifying a verb; "predicted" serves as a participle, not an adverb. Step 6: Option C: "Sneha was a kind person, but she hated people who spread rumors." It has the conjunction "but", but does not clearly include any adverb. Step 7: Option D: "Do you want the shrimp or the crab?" includes the conjunction "or" but no adverb.

Verification / Alternative check:
To verify, underline the conjunction and adverb in each option. Only in sentence A do we find a typical adverb of manner ending with "-ly" ("silently") and a clear coordinating conjunction ("but") linking contrasting clauses. In the other sentences, we either have only a conjunction or no convincing adverb, confirming that A is the only sentence fulfilling both requirements simultaneously.

Why Other Options Are Wrong:
- Option B lacks a straightforward adverb; "predicted" is not functioning as an adverb of manner modifying a verb like "caused".
- Option C has a conjunction "but" but does not contain any explicit adverb such as "kindly" or "strongly".
- Option D uses "or" as a conjunction to link "the shrimp" and "the crab", but again, no adverb is present.
Thus, these options do not meet the requirement of containing both parts of speech together.

Common Pitfalls:
Learners sometimes confuse adjectives and adverbs, especially when they modify different parts of a sentence. They may also assume that any connecting word is a conjunction, even if it is a preposition. Paying attention to what each word is modifying or joining clarifies whether it is an adverb or a conjunction. Remembering that adverbs often answer "how", "when", or "where" and that conjunctions connect clauses or items on a list helps in making the correct choice.

Final Answer:
The sentence that contains both an adverb and a conjunction is Adam crept silently up the stairs, but could not slow his heartbeat.