Consider languages L and L_{1}, each over the alphabet {a,b }, where
L_{1} = \left \{w \mid w contains some x \in L as substring \right\}
Which of the following must be true about L and L_{1} ?
I. If L is regular, then L_{1} is regular.
II. If L is context-free, then L_{1} is context-free.
III. If L is recursive, then L_{1} is recursive.
(A) I only (B) III only (C) I and III only (D) II and III only (E) I, II, and III
