It's a state in which a person has apprehensions all the time about their well-being and considers that they are ill.

Hypochondria is the psychological condition where a person constantly fears they are ill despite having no (or mild) symptoms. This matches the description: "apprehensions all the time about well-being". Hence Option C should be the correct choice here. 

Hypoallergenic is something that is designed to minimise allergic reactions, and hypochondriac is a person who has hypochondria. 

Since the question talks about a "state" , the best choice here is hypochondria, making C the correct choice.