Find the part of the sentence that contains an error: The authority’s choice to delay the rollout (1)/ was linked partly to pressure from the industry (2)/ and partly because of legal uncertainty (3)/ related to the latest amendments. (4)

The correct answer is (3).

Explanation:
The error lies in part (3) of the sentence due to a lack of parallel structure (parallelism).

In English grammar, when elements are connected by correlative or repeated structures like "partly... and partly...", they must be structurally parallel (i.e., use the same grammatical form).

Let's analyze the two paired parts of the sentence:

1. "partly to pressure from the industry" — Here, "partly" is followed by a prepositional phrase starting with "to".

2. "and partly because of legal uncertainty" — Here, "partly" is followed by the prepositional phrase "because of".

To maintain parallel construction with part (2), part (3) should also use the preposition "to" instead of "because of":
"...was linked partly to pressure from the industry (2) / and partly to legal uncertainty (3)..."

Therefore, section (3) contains the grammatical error.