Select the word-pair in which the two words are related in the same way as are the two words in the following word-pair.

Doctor : Cardiologist

Engineer : Chemical Engineer

Doctor : Cardiologist

The logic followed here is :

Doctor : Cardiologist ⇒ Cardiologist is a doctor who specializes in the study of heart diseases and heat abnormalities

Similarly

Engineer : Chemical Engineer ⇒ Chemical Engineer  is a Engineer who possesses chemical and mechanical  knowledge