Linear Bound Automata
A non-deterministic TM is called linear bound automata (LBA) if,
- It's input alphabet includes two special symbols $\varnothing$ and $\$$ as left and right end markers.
- It has no moves beyond thee end markers, i.e, no left move from $\varnothing$ and no right move from $\$$.
- It never changes the symbols $\varnothing$ and $\$$.
LBA accepts CSL. Hence option is C.
Theorem: If L is a CSL, then L is accepted by some LBA.