Then add five pairs of your own explaining their connotative differences

1. Crippled, Disabled 
Crippled is almost sound like a discriminating word and have a negative connotation where as disabled is more polished and reverent.
 2. Relaxed, Easy-going
 Both seem same but relaxed refers to free, pleasure and stress free but easy-going implies not serious and laziness.
 3. Knockout, Beautiful
 Knockout mainly used to imply someone is sex y where as beautiful is simple compliment for a person.
 4. Young, Immature
 Sometimes both are used in the same context but youth may be always a substitute for immature.
 5. Skinny, Thi n Both are almost similar but actually someone skinny is called thin.

The answer would be choice b