For the first one the correct answer is variant A because of the appositive developed phrase ' <span>grown in many parts of the world ' .
For the second one the correct answer is variant B because that sentence doesn't need any comma's like the other ones.</span>
In my opinion, learning does continually have a positive effect on a person life. Learning new things give you a broader knowledge and experience. Learning is ongoing and will always be of positive gain in the right context.
