Assume a program has the following variable definitions: int units; float mass; double weight; and the following statement: weight = mass * units; Which automatic data type conversion will take place? A) mass is demoted to an int, units remains an int, and the result of mass * units is an int. B) units is promoted to a float, mass remains a float, and the result of mass * units is a float. C) units is promoted to a float, mass remains a float, and the result of mass * units is a double.

In the given code, there are three variable definitions: 1. int units; 2. float mass; 3. double weight; 'int' is an integer data type, 'float' is a single-precision floating point data type, and 'double' is a double-precision floating point data type.

When performing an operation between two different data types in a programming language like C++, automatic data type conversion is carried out. The data type's conversion depends on their precision and the order is as follows: 1. int 2. float 3. double Higher precision data types can represent a lower precision data type without losing any information. For example, a float value can be upcasted to a double without losing any float precision. On the other hand, the lower precision data type needs to be promoted (upcasted) to the higher precision data type (if used together) to perform the operation.

Now, compare the given options with the automatic data type conversion rules that we mentioned earlier. Let's analyze each of them. A) mass is demoted to an int, units remains an int, and the result of mass * units is an int. - This option is incorrect, since a float should not be demoted to an int. B) units is promoted to a float, mass remains a float, and the result of mass * units is a float. - This option is incorrect. While the promotion of units to a float is correct, the result should not be a float, because the target variable, weight, is a double, and it would require a conversion from float to double. C) units is promoted to a float, mass remains a float, and the result of mass * units is a double. - This option is correct, as it properly promotes the int variable (units) to a float, and the result of the operation is a double (matching the target variable, weight). So, the correct answer is: Option C) units is promoted to a float, mass remains a float, and the result of mass * units is a double.