The factors of 28 are:

1,2,4,7,14,28

So the sum of the reciprocals are:

$\frac{1}{1} + \frac{1}{2} + \frac{1}{4} + \frac{1}{7} + \frac{1}{14} + \frac{1}{28}$

Let's put 2 on the right side of this, and figure out what sign should go between them (=,<,>, or undetermined). To denote the sign, I'll use $?$.

$1 + \frac{1}{2} + \frac{1}{4} + \frac{1}{7} + \frac{1}{14} + \frac{1}{28}$ $?$ $2$

Let's multiply both sides by 28:

$28($$1 + \frac{1}{2} + \frac{1}{4} + \frac{1}{7} + \frac{1}{14} + \frac{1}{28})$ $?$ $28(2)$

The result is:

$28 + 14 + 7 + 4 + 2 + 1$ $?$ $56$

$56$ $?$ $56$

So we know that $?$ is actually $=$.

The answer therefore is C