This output is 
4 2 4

Explanation:
sizeof('1 or 2 or 3,......or n')=4

sizeof("0")=2
sizeof("10")=3
sizeof("100")=4
sizeof("1000")=5
sizeof("10000")=6
.
.
.
.
.
sizeof("n")=n

sizeof(1 or 2 or 3......or n)=4

1  2  4

4 2  4

sizeof('3')  means it will take ascii value which is an 
integer, it shows size of integer.

sizeof("3")  means, here it will treat it as an array, it 
will print size of an array, so array contain '3' and '\0'
so out put is 2.

try  size("3ashwin") it will give 8 as out put.

sizeof(3) means directly we asking size of an integer.

thank you 

if is an wrong answer plz write correct answer to

molugu.ashwin@gamil.com

Answer is : 1 2 2 
because 

sizeof('3')takes 3 as character and so, size of a character
is 1 byte

sizeof("3") takes 3 as a string so, here strinf contains one
character 3 and end character '\0'. so, sizeof("3") gives o/p 2 

and
sizeof(3) takes 3 as integer so size of an integer is 2 bytes

answer is :1 2 2 ;

size('3')means character constant so it is short int size it
will ocupi 1.

size("3")it will treated as string. 2

size(3) it is integer 2

o/p 1 2 2
sizeof('3')takes 3 as character and so, size of a character
is 1 byte

sizeof("3") takes 3 as a string so, one
character 3 and end character '\0'. so, sizeof("3") gives 
o/p 2 

and
sizeof(3) takes 3 as integer so size of an integer is 2 
bytes

2 2 2

I compiled this in system,this is correct answer.check it
once...............