Select the grammatically correct sentence.
A. It is a old uniform but a memorable thing for me.
B. It is old uniform but a memorable thing for me.
C. It is the old uniform but memorable thing for me.
D. It is an old uniform but a memorable thing for me.

Correct option is A

The grammatically correct sentence is "It is an old uniform but a memorable thing for me." This sentence correctly uses the indefinite article "an" before "old uniform," which begins with a vowel sound, and includes the necessary article "a" before "memorable thing." The other options contain errors in article usage or structure.