Easily changed and controlled by other forces suggests malleable and susceptible. Susceptible means likely to be harmed by something, which means can be changed by forces.

After reading the sentence, it's clear that the part after the ',' given meaning to the word in the '_____' i.e easily changed, and controlled by outside forces

Hence the word Malleable - (metaphorical) Flexible, liable to change and susceptible - 1. Likely to be affected by something
2. Easily influenced or tricked; make the best answer.

Regards

The obvious clue is clearly "can easily change", which matches with malleable and prosaic!

malleable and susceptible are the only pairs possible - need not read the question, but here is the logic:

, easily changed, and controlled by outside forces

idea before and after the comma should mean the same thing

easily controlled ----> susceptible

pick:
malleable and susceptible

I found no clear and lucid explanation from the site. GMAT prep CLUB far better then GRE prep club for math, RC

Well.

usually on quant we do have the support of Brent from GreenLightTestprep and his explanations are amazing and very comprehensive. 80 of the questions here are explained by him

On RC depends who asks for explanations and to what extent. I reply to all of them.

Gmatclub has more users so there is more chance to came across with more explanations. However, We support the board strongly.


Hope this helps

Why not Influential ? This is also same as susceptible, malleable, impressionable