Use the table below to answer the following question.

DPMO stands for Defects Per Million Opportunities.

$\backslash$table$[[+-,$DPMO$],[3,2700],[4,63],[5,\mathrm{.}57],[6,\mathrm{.}002]]$

A product delivery service company claiming $2\mathrm{.}1$ million consecutive on$-$time deliveries is performing at:

a$.$ less than $3$ sigma.

b$.$ between $3$ and $4$ sigma.

c$.$ between $4$ and $5$ sigma.

d$.$ between $5$ and $6$ sigma.

e$.$ better than or equal to $6$ sigma.