Recognizing the sequence 1/16, 1/8, 3/16, 1/4, 5/16, ... 
What is the missing number?
  $$\frac{1}{16}, \frac{1}{8}, \frac{3}{16}, \frac{1}{4}, \frac{5}{16}, \ \ \  [?]$$

$$A. \frac{5}{4}\quad B. \frac{3}{4}\quad C. \frac{5}{8}\quad D. \frac{3}{8}$$
Spoiler: Answer is $D$, but I don't know why.
Thanks

Another sequence-recognizing technique
is to look at the difference between consecutive terms.
In this case,
$\frac{1}{8}-\frac{1}{16}
= \frac{1}{16}
$,
$\frac{3}{16}-\frac{1}{8}
= \frac{1}{16}
$,
$\frac{1}{4}-\frac{3}{16}
= \frac{1}{16}
$,
and
$\frac{5}{16}-\frac{1}{4}
= \frac{1}{16}
$.
Since the difference between
consecutive terms is
$\frac{1}{16}$,
the next term should be
$\frac{5}{16}+\frac{1}{16}
=\frac{6}{16}
=\frac{3}{8}
$.
