Wave on a string general theory

[ObviousManiac]

Homework Statement

The figure shows a wave on a string moving to the right. For each of the points indicated on the string, A-F, state whether it is moving:
I. upward,
II. downward,
III. instantaneously at rest.

Homework Equations

N/A

The Attempt at a Solution

I got A and D as (III), B and C as (II), and E F as (I).

According to the answer, my B-C and E-F is mixed up, but I'm not sure why. How is it moving upward at B? Downward at E? I'm sure I'm just missing something simple.

 

[ObviousManiac]

Also, it asks "In the previous problem, which points have the greatest and least accelerations?"

I'm kinda lost there, but my guess would be C (greatest?) and F (least?)