根据下面资料，回答52-55题
Heahh care experts have long drawn attention to the problems of eating too much sah．There isstrong evidence that a diet high in salt can lead to raised blood pressure．Since high blood pressure is amajor factor in heart disease．it makes sense to cut down on the salt people eat．
In the past，food contained very little salt，and people added it to their food at the table．Very fewpeople  add  salt this  way  nowadays．However，the  salt  content  of processed  foods has  gone  updramatically．It’s now estimated that over three．quarters of the salt in the average diet comes fromprocessed foods，eaten without our being aware of it．
Salt is added to food partly to extend shelf-life．but more often it’s dropped in to make up for theflavor lost in the manufacturing process．This is especially true of ready meals and highly processedfoods．but it’s also true of such basic food as biscuits，soups，and even bread．Much mass—producedbread，for instance．contains so much salt．half a gram for every hundred grams of bread--that it’sofficiallv classified bv the UK government as high——salt food．Salt has to be added to the bread becausefast Droduetion cuts down the time for the flavor to develop．Without added salt，the bread would tastelike paper．
In the UK，the government has launched a campaign to cut down on the salt people eat．The UK Food Standards Agency argues that nearly half of the UK’s population eat too much salt—9．5 9 a day onaverage．Its aim is to bring down the average t0 69 a day．The idea is to cut the salt content in 85 keyfood categories such as bread．meat．and cakes．
What is the main reason for reducing salt in food?

A To improve the flavor of food．

B To decrease the time for processing food．

C To extend the shelf．1ife of food．

D To protect people against heart diseases．