a$.$ There are several reasons listed in the article as to why you should be very cautious about online reviews. Which one of the following is not one of the first three reasons listed in the article?

i$.$ The marketplace for fake reviews operates fairly openly.

ii$.$ The Russians are known to plant positive reviews for socially detrimental consumer goods.

iii. Companies give freebies in exchange for reviews.

iv$.$ Even if you think you can spot fake reviews, you probably can't.

b$.$ What was VIP doing to boost the ratings of its Kindle Fire cover?

i$.$ Supplying a discount code for use in a Kindle Fire purchase if they posted a review.

ii$.$ Reimbursing customers for the cover if they posted a review.

iii. Falsely upgrading customers' credit ratings if they posted a review.

iv$.$ Sending customers gift cards for iTunes if they posted a review.

c$.$ How well did people perform in spotting fake reviews?

i$.$ They were right about $90\%$ of the time.

ii$.$ They were right about $10\%$ of the time.

iii. They were right about $17\%$ of the time.

iv$.$ They were right about $50\%$ of the time.