0-1 periodic sequences have important applications in communication technology. If a sequence $a _ { 1 } a _ { 2 } \cdots a _ { n } \cdots$ satisfies $a _ { i } \in \{ 0,1 \} ( i = 1,2 , \cdots )$ and there exists a positive integer $m$ such that $a _ { i + m } = a _ { i } ( i = 1,2 , \cdots )$ , then it is called a 0-1 periodic sequence, and the smallest positive integer $m$ satisfying $a _ { i + m } = a _ { i } ( i = 1,2 , \cdots )$ is called the period of this sequence. For a 0-1 sequence $a _ { 1 } a _ { 2 } \cdots a _ { n } \cdots$ with period $m$ , $C ( k ) = \frac { 1 } { m } \sum _ { i = 1 } ^ { m } a _ { i } a _ { i + k } ( k = 1,2 , \cdots , m - 1 )$ is an important index describing its properties. Among the following 0-1 sequences with period 5, the one satisfying $C ( k ) \leqslant \frac { 1 } { 5 } ( k = 1,2,3,4 )$ is
A． $11010 \ldots$
B． $11011 \cdots$
C． $10001 \cdots$
D． $11001 \cdots$