Declarations and Initializations - Programming

Which of the structure is incorrcet?

1 :	`struct aa { int a; float b; };`
2 :	`struct aa { int a; float b; struct aa var; };`
3 :	`struct aa { int a; float b; struct aa *var; };`

A 1

B 2

C 3

D 1,2,3

ANS:A - 1

Option B gives "Undefined structure in 'aa'" error.

Which of the structure is incorrcet?

1 :
`struct aa { int a; float b; };`

2 :
`struct aa { int a; float b; struct aa var; };`

3 :
`struct aa { int a; float b; struct aa *var; };`