C. It has been said that there are other ways to solve the problem.
This is because it shows that the author has investigated other possible solutions and not just the one that they are writing about. All of the other answers just support the claim without mentioning anything else.
Answer:
There does not need to be after insisted.
Explanation:
Answer: The researchers used several methods for testing their data, the article explains them all.
Explanation:
I'm no english teacher but I believe the use of the comma after data should've been a period and the T in <em>the</em> should've been capitalized.
There's more to the word reproduce than that...
Example:
High elevations reproduce the physical conditions of high latitudes.
This robot will reproduce the characteristics of Barack Obama.
