+0
Which variations are incorrect and why?

Which are/is the best?

Thank you Emotion: big smile

a. As to the water shortage, I'm not exactly sure what you are worried about.

b. I'm not exactly sure what you are worried about as to the water shortage.

c. As for the water shortage, I'm not exactly sure what you are worried about.

d. I'm not exactly sure what you are worried about as for the water shortage.

e. Regarding the water shortage, I'm not exactly sure what you are worried about.

f. I'm not exactly sure what you are worried about regarding the water shortage.

g. Concerning the water shortage, I'm not exactly sure what you are worried about.

h. I'm not exactly sure what you are worried about concerning the water shortage.

i. With regard to the water shortage, I'm not exactly sure what you are worried about.

j. I'm not exactly sure what you are worried about with regard to the water shortage.

k. With regards to the water shortage, I'm not exactly sure what you are worried about.

l. I'm not exactly sure what you are worried about with regards to the water shortage.

m. In regards to the water shortage, I'm not exactly sure what you are worried about.

n. I'm not exactly sure what you are worried about in regards to the water shortage.

o. In regard to the water shortage, I'm not exactly sure what you are worried about.

p. I'm not exactly sure what you are worried about in regard to the water shortage.
+0
American Heritage Dictionary Usage Notes:

1. Although sometimes considered poor substitutes for about or concerning, the phrases as regards, in regard to, and with regard to are standard and occur in all varieties of spoken and written English, especially in business writing: As regards your letter of January 19. ... In regards to and with regards to are widely rejected as errors.

2. Regard is traditionally used in the singular in the phrase in regard (not in regards) to. Regarding and as regards are also standard in the sense "with reference to." In the same sense with respect to is acceptable, but respecting is not.·Respects is sometimes considered preferable to regards in the sense of "particulars": In some respects (not regards) the books are alike.
Comments  
Hi,

Thank you

What about 'as to' and 'as for' above?