The word agitated has been derived from the Latin word- Agitat, which suggests to be driven.
We know the meaning and therefore the origin of the word agitated. Now, let’s study its usage:
Example- He was so agitated he could hardly eat anything. Here, we will understand that X was quite nervous or anxious about something that it kept him from eating anything.
Let’s examine the given options-
a)Upset- It means to feel distressed or flustered about something. it's similar in assuming to agitated. Hence, it's the proper option.
Example- The boy gets upset when his mother leaves the space.
b)Angry- It means to feel furious or outraged by something or someone. it's different in aiming to agitated. Hence, it's an incorrect option.
Example- She gets angry at little things.
c)Serious- It refers to something that needs urgent attention. it's different in aiming to agitated. Hence, it's an incorrect option.
Example- He has been called to the office for a heavy matter.
d)Unhappy- It refers to someone who is miserable or heart-broken by something. it's different in assuming to agitated. Hence, it's an incorrect option.
Example- They lived together despite their unhappy marriage.
The correct answer is Option ‘a’.