To answer this question, we need to understand the different types of ABAP data statements and determine which one is not valid.
Option A) Data fielda(5) type c - This option is valid. It declares a character type data field named 'fielda' with a length of 5.
Option B) Data fielda(5) type n - This option is valid. It declares a numeric type data field named 'fielda' with a length of 5.
Option C) Data fielda(5) type t - This option is not valid. 't' is not a valid data type in ABAP.
Option D) Data fielda(5) type x - This option is valid. It declares a hexadecimal type data field named 'fielda' with a length of 5.
The correct answer is C. This option is not valid because 't' is not a valid data type in ABAP.