If the strings of a language L can be effectively enumerated in lexicographic (i.e., alphabetic) order, which of the following statements is true?

Question

(A) L is Regular (b) L is context free but not necessarily Regular (c) L is recursive but not necessarily Regular (d) L is recursively enumerable but not necessarily Recursive

I could only conclude that L is recursively enumerable from above statement but then why is it recursive ?