All of the following are considered to be drawbacks of local marketing EXCEPT:

Its Option C..........................it can attract unwanted competition.

>>>>>>>>>>>>>>  c. it can attract unwanted competition. >>>>>>>>>>>>>

b. it can create logistical problems when the company tries to meet varied requirements.

Definitely C is the most logical answer as it It can attract unwanted competition. 

c. it can attract unwanted competition.

 it can drive up manufacturing and marketing costs by reducing economies of scale.

Undoubtedly C would be the answer

Non of the above is an absolute drawback.

If you consider any aspects of marketing as a drawback, refrain yourself from being in marketing!!

Forget humans, even Gods needs marketing!! locally, regionally,continentally and so on...!! 

Most Definitely option C  

it can attract unwanted competition. 

What is meaning of reducing economies of scale