The $\Delta$ operation on the set $\mathrm { A } = \{ \mathrm { a } , \mathrm { b } , \mathrm { c } , \mathrm { d } , \mathrm { e } \}$ is defined by the table below. For example, a $\Delta \mathrm { d } = \mathrm { c }$ and $\mathrm { d } \Delta \mathrm { a } = \mathrm { a }$.
| $\Delta$ | a | b | c | d | e |
| a | a | b | a | c | d |
| b | c | b | b | a | e |
| c | a | b | c | d | e |
| d | a | a | d | d | b |
| e | e | e | e | d | a |
According to this table, which of the following subsets of set A
- $\mathrm { K } = \{ \mathrm { b } , \mathrm { c } , \mathrm { d } \}$
- $\mathrm { L } = \{ \mathrm { a } , \mathrm { b } , \mathrm { c } \}$
- $\mathrm { M } = \{ \mathrm { c } , \mathrm { d } , \mathrm { e } \}$
are closed under the $\Delta$ operation?
A) Only K
B) Only L
C) K and L
D) K and M
E) L and M