A. Greatly reduced the assembly time for each car.
Answer:
The second one: You are, if I'm not mistaken, a good person for this experiment.
Explanation:
The first sentence, "You are, if I'm not mistaken a good person, for this experiment." does not have a comma after "mistaken", where there should be one. After "a good person", there should not be a comma.
A coordinating conjunction is a word that joins two elements of equal grammatical rank and syntactic importance. They can join two verbs, two nouns, two adjectives, two phrases, or two independent clauses. The seven coordinating conjunctions are for, and, nor, but, or, yet, and so.