The question asks how to declare a variable in Kotlin that cannot be reassigned after it is initialized. The example provided in the question, val pi = 3.14 // 'pi' cannot be reassigned, directly illustrates the answer. Let's examine the options: Using the val keyword: In Kotlin, val is used to declare a read-only property (or an immutable reference). Once a val variable is initialized, its value cannot be changed or reassigned. This perfectly matches the requirement. Using the let keyword (used for scoping functions): The let keyword is a scope function in Kotlin, primarily used to execute a block of code on an object and return the result of the lambda. It is not used for variable declaration. Using the var keyword (allows reassignment): The var keyword is used to declare a mutable variable, meaning its value can be changed or reassigned after initialization. This is the opposite of what the question asks. Using the const keyword (only for compile-time constants): The const keyword is used to declare compile-time constants. These are also immutable, but const can only be used with val and for primitive types or Strings, and must be declared at the top level or inside an object or companion object. While const variables cannot be reassigned, the most general and fundamental way to declare a variable that cannot be reassigned after initialization is using val. The example given in the question uses val. Therefore, the correct way to declare a variable that cannot be reassigned after initialization is by using the val keyword. The correct option is: Using the val keyword