Biểu thức nào sau đây cho x có giá trị dương:

The question asks which expression assigns a positive value to `x`. We need to consider the bitwise shift operators and the data type of `x`. * **Option 1: `int x = -1; x = x >>> 5;`** * `x = -1` (in binary, all bits are 1). * `x >>> 5` is an unsigned right shift by 5 bits. This shift pushes the last 5 bits out and inserts 5 zero bits at the beginning. Because `x` initially has all bits as 1, after the unsigned right shift, the upper bits are filled with 0, so `x` becomes a positive number. * **Option 2: `int x = -1; x = x >>> 32;`** * `x = -1`. * `x >>> 32` is equivalent to `x >>> 0`, because only the last 5 bits of the right-hand operand are used to calculate the shift amount in Java (since the data type of x is `int` - 32 bits). Therefore, `x` remains -1. * **Option 3: `byte x = -1; x = x >>> 5;`** * `byte x = -1`. * When `x` is a `byte`, it will be automatically promoted to `int` before performing the unsigned right shift. Therefore, `x >>> 5` is similar to option 1, i.e., the value will be positive. However, the data type of x is now `int`, not `byte` anymore. * **Option 4: `int x = -1; x = x >> 5;`** * `x = -1`. * `x >> 5` is a signed right shift. This shift pushes the last 5 bits out and inserts 5 sign bits (in this case, 1) at the beginning. Therefore, `x` remains a negative number. Thus, the correct answer is option 1, because after the unsigned right shift, `x` will have a positive value.