The correct answer is D) the subject complement of this sentence is human. A subject complement is a word (usually a noun) which follows a linking verb (which connects two parts of a sentence - in this sentence, the linking verb is <em>was</em>), and refers to the subject of the sentence. Here, the word human refers to the subject Neil Armstrong, he is that human.
<span>Effective decision making means comparing the additional costs of the alternatives with the benefits. For example, you could perform a cost-benefit analysis. This is a common technique to aid decision making.</span>
