Total cholesterol level = a+b (calorie intake) + c (physical activity) + d (body mass index); is an example of :
The total cholesterol level in the given question is shown to depend on several (multiple) independent variables viz. calorie intake, physical activity and body mass index. It is thus an example of multiple regression. Also the relationship depicted in the equation is not logarithmic (log) but linear and hence multiple linear regression is the answer here. Ref: High Yield Biostatistics By Anthony Glaser, Page 49
Simple linear regression
Simple curvilinear regression
Multiple linear regression
Multiple logistic regression