What is the best way to combine sentences 2 and 3?
A.
Salt is a very common ingredient in many foods, and it is so widespread that doctors today warn us about getting too much of it.
B.
Salt is a very common ingredient in many foods only if salt is so widespread that doctors today warn us about getting too much of salt.
C.
Salt is a very common ingredient in many foods as long as it is so widespread that doctors today warn us about getting too much of it.
D.
Salt is a very common ingredient in many foods; finally, salt is so widespread that doctors today warn us about getting too much of it.

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The Story of Salt

(1) Salt is one of those things that we often take for granted. (2) Salt is a very common ingredient in many foods. (3) It is so widespread that doctors today warn us about getting too much of it. (4) Because it is everywhere, some people are surprised to learn that salt used to be a highly prized good. (5) In the past, salt was often so precious that it was used like money. (6) In fact, people were not worried about getting too much salt, but having too little of it.
(7) The word "salary" even comes from the Latin word for salt, sal. (8) This is based upon the Roman custom of paying soldiers with salt. (9) Soldiers were given extra money so they could buy salt of their own. (10) China used salt for currency, trading it along with silk. (11) The Chinese also used salt as an important ingredient in medicine. (12) One site for salt cultivation in China dates back more than 6,000 years. (13) Salt used to be so important that it was used as a form of payment in many cultures. (14) Ancient Egyptians included salt in the tombs of their kings, along with gold and silver. (15) In addition, an ancient Egyptian recipe from 1600 B. C. explained how to use salt to treat infection. (16) Today, people know that salt is an essential ingredient for their brains, muscles, and cells.
(17) Another reason why salt was so important is because it can be used to preserve foods. (18) Before the invention of refrigeration, preserving food in salt was one of the best ways to keep foods from rotting. (19) For thousands of years, people covered meats and fish in salt to remove moisture from the food. (20) Today, using salt is still a common technique for preserving food.
(21) The next time you are enjoying a bag of potato chips, eating corn on the cob, or baking bread, think about the salt you are using as part of your meal. (22) Think about the role that salt has played throughout history.