A query can be written in safe Relational Calculus if and only if it can be written in Relational Algebra means it can be written in Relational Calculus as well as Relational Algebra, but Relational calculus also have some unsafe operations and because of those unsafe operations sometimes create ∞(infinite) loop.
So we can say that all safe relational calculus query can be translate into relational algebra
So Option (C) is the correct answer