A common computer programming rule is that names of variables must be between one and eight characters long. The first character can be any of the $26$ letters, while successive characters can be any of the $26$ letters or any of the $10$ digits. For$$ example, allowable variable names include$$ A$,$ BB$,$ and M$3477$K$.$ How many different variable names are$$ possible? $($Ignore the difference between uppercase and lowercase$$ letters.$)$

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Part $1$

Choose the correct answer below.

A$.$

$208$

B$.$

$2,095,681,645,538$

C$.$

$75,444,539,239,368$

D$.$

$2,037,468,266,496$