Choose the sentence that correctly and naturally describes an intricately engineered biological system like the human body.

Introduction / Context:
This sentence improvement question tests your awareness of standard patterns after the word such in English, especially when comparing something specific like the human body with a general category. It also checks that you notice agreement between possessive pronouns and nouns, such as our and ours.

Given Data / Assumptions:
The core idea is that an intricately engineered biological system like the human body seems unlikely to have arisen purely from random changes. The versions differ in the use of such, such as, and in whether they follow these with the pronoun our or the pronoun ours. We assume that the intended style is formal, scientific, and grammatically precise.

Concept / Approach:
There are two common patterns with such in English. One is such a system as ours, where such is followed by a noun phrase and then as plus a possessive pronoun in independent form. Another is such a system as our body, where our directly modifies a noun. Using such and such as together before the same noun phrase is redundant and ungrammatical. Further, our must be followed by a noun, as in our system, while ours stands alone as a possessive pronoun that replaces a full noun phrase.

Step-by-Step Solution:
First, read option A. It uses such an intricately engineered bio system as ours, which is a well known and correct comparative structure.Second, read option B. It says such an intricately engineered bio system such as our. Here such and such as are both used and our is left without a following noun, so the phrase is faulty.Third, read option C. It drops the article an and still uses such and such as our with no noun after our, which creates two errors at once.Fourth, read option D. It says such intricately engineered bio system such as ours, which again repeats such and such as and also omits the article an before the singular noun system.Finally, compare all four options. Only option A applies the standard pattern such a system as ours with correct article use and pronoun form.

Verification / Alternative check:
We can test the pattern by replacing bio system with simple word system. Phrases like such a system as ours are common in formal writing and are easily found in serious prose. In contrast, such system such as our would always be edited in published material because of redundancy and the incomplete possessive. This confirms that option A is the only fully acceptable choice.

Why Other Options Are Wrong:
Option B is wrong because it combines such with such as in a single continuous phrase and leaves the possessive pronoun our without a noun. Option C not only repeats such but also removes the article an before a singular count noun. Option D repeats such with such as and still lacks the required article. These combinations produce ungrammatical and unnatural phrases, so they cannot be chosen.

Common Pitfalls:
Students often overuse such as because they see it frequently in examples and lists. However, the construction such a system as ours is different and does not require such as. Another pitfall is confusion between our and ours. Remember that our always needs a noun after it, while ours replaces a full noun phrase previously understood from context. Keeping these small but important distinctions in mind will help you handle many similar questions in exams.

Final Answer:
The best version is At first glance, it seems implausible that such an intricately engineered bio system as ours could have come about merely as a result of random modifications.