Which of these terms, Impurity, Imperfection, Point Defect, Interfacial Defect, Linear Defect best describes the following sentences?

a$)$ A deviation from atomic$/$molecular order and$/$or continuity

b$)$ A defect associated with one atomic site

c$)$ A one$-$dimensional defect

d$)$ A two$-$dimensional defect

e$)$ An atom of a different element than the other atoms in the structure