Answer:
It's option d - Negative acceleration
Explanation:
- Let's start by demonstrate why <em>it's not option b - Speed : </em>Speed is a scalar quantity so it can not be represented by a vector
- Let's check that <em>the green vectors represent velocity</em> (velocity is a vector quantity, velocity is a direction aware, while speed is just a scalar)
- Now let's show that the circled vectors are acceleration vectors:
Mathematically position X , velocity V and acceleration A are:
and 
Where X, V, A are vectors and
indicates the derivate a of a time is equal to b.
So, this show that acceleration is a rate respect of time of velocity ⇒ When acceleration is positive, velocity increments, when acceleration is negative, velocity decrements.
<em>The above explanation correspond to the motion map shown, getting demonstrated that the answer is D - Negative acceleration </em>