1 .
A password consists of 28 characters, each character being a lowercase letter. A password must
contain exactly one vowel (i.e., a, e, i, o, or u).
How many passwords are there?
(a)
$28 \cdot 5 \cdot 26^{27}$
(b)
$5 \cdot 21^{27}$
(c)
$28 \cdot 5 \cdot 21^{27}$
(d)
$28 \cdot 5 \cdot 27^{21}$