제가 고른 답이나 해답지는 ==이렇게 표시했습니다. 그런데, 달리 생각한 분이 계셔서요. 모두 paraphrasing 한 것 같은데..

제가 표시한 것이 답이 아닐 경우 간단한 설명과 함께 지적 부탁드립니다.

3번은 약간 이상하게 paraphrasing된 것 같기도 하구요..
1. A product, even one that has excellent packaging, may get lost on the shelf among the other products. ==b

a) Unless a product has a really great package, stores will lose it among other similar products.

b) Although a product might be in a good package, customers might not notice it.

2. The predominant religion in South America is Catholicism. ==a

a) Catholicism is the most widespread religion in South America.

b) Most other religions in South America dominate Catholicism.

3. While marking, readers are actively searching for the key information. ==a

a) Readers look for key words or phrases to mark.

b) Readers inform learners about topics.