Suppose you are given the following binary classification problem where $"+"$

represents positive class and $"-"$ represents negative class. Which one of the following

value of $k$ in $k-$nearest neighbors would give the LOWEST leave$-$one$-$out cross

validation accuracy?

a$\mathrm{.}5$

b$\mathrm{.}4$

c$\mathrm{.}3$

d$\mathrm{.}1+,+$

$+,-$

$+,-$