When multiple data types are involved in operations at the same time, the following principles must be followed:

1. If double-precision types are involved in operations, the result must be double-precision;

2. Operation between integer type and long integer type, the result is long integer type;

3. Operation between integer type and single precision type, the result is single precision type;

4. Operation between long integer type and single precision type, the result is double precision type.

Based on point 1 above, it can be seen that the result of the question is D, double precision