Assume a program has the following variable definition:

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 remains a float stored in a double variable

C$.$ units is promoted to a float, mass remains a float, and the result of mass $*$ units is a promoted to a double for storage

D$.$ No automatic conversion takes place and an runtime error is generated.