Final answer:
The correct data types for the given code segment are 'double' for variable x, which holds the decimal value 0.5, and 'boolean' for variable y, which holds the true/false value true. Therefore, option D is the correct answer.
Step-by-step explanation:
The question is related to variable data types in programming. To determine the correct data types for variables x and y, one needs to analyze the type of values assigned to them. The value 0.5 assigned to variable x is a decimal number, which means the data type should support floating-point numbers. Therefore, x should be a double. The value true assigned to y is a boolean value, indicating a true or false condition, which means the data type for y should be a boolean. Hence, the correct answer to which data types should be used to replace /* data type 1 */ and /* data type 2 */ is D: The variable x should be declared as a double and the variable y should be declared as a boolean.