Japanese researchers are producing a series of robots

[PrakharS433]

Not the researchers, but the robots respond to the facial expressions. E uses 'responding' which is parallel to 'producing', which would mean that the researchers respond. In C, the robots respond to the facial expressions: 'respond' is parallel to 'can identify'.

correct.

this is an excellent example of the following general principle:
parallelism must be both LOGICAL and GRAMMATICAL.
in other words, you're going to use grammatical parallelism to figure out the correct answer - but you have to use LOGICAL parallelism to figure out WHICH words must be parallel in the first place.
as the poster above has indicated, you have to use a logical understanding of the sentence to figure out that 'respond' needs to be parallel to 'identify' (NOT 'producing'), because both of those are actions of the robots, not the researchers.

Hi Ron,

I eliminated Option A and E as it mentions that "Goal is creating a robot " GOAL is not creating robot, instead scientists goal is to create a robot.

Is this correct reasoning to eliminate option A and E.?

[RonPurewal]

not really, since __ing forms are also nouns.
e.g.,
The greatest challenge for many authors is writing the first few words of a book.

[Crisc419]

Here in option A " robot that will empathize with us" is not a clause right so we need another subject + verb set up as given in option C, the correct answer

(a) has a clause after the semicolon. its subject and verb are, respectively, "goal" and "is".

here are a couple of things about (a) that are actually problematic:
* the first "they" could potentially refer either to the robots or to the researchers.
* "their goal is creating" seems to suggest that the goal is actually creating something. i.e., the goal itself is sitting at a desk, doing work.
* most notably, "primarily" is in the wrong place. in choice (a), it appears to describe "creating"; this doesn't make any sense. we're talking about the #1 goal of the researchers, so "primary" should be an adjective in front of "goal".

For the same reason we can eliminate B right as we need a clause after the semi-colon.

yes, that part of (b) is actually a fragment.

Ron, could you explain more about "their goal is creating" ? i cannot understand your explaination well. thanks a lot.

[RonPurewal]

I am writing a forum post right now.
this is what i'm doing at the moment -- i'm writing a forum post.

James is creating a new xxxx.
this is what james is doing at the moment -- he's creating something.
this same reading is very problematic here.

clearly, this is not the #1 thing wrong here.

[Crisc419]

I am writing a forum post right now.
this is what i'm doing at the moment -- i'm writing a forum post.

James is creating a new xxxx.
this is what james is doing at the moment -- he's creating something.
this same reading is very problematic here.

clearly, this is not the #1 thing wrong here.

do you mean inanimate objects cannot be the subject of some action?

for instance，

my job is writing novels.
---incorrect?

[RonPurewal]

this is a multiple-choice test. if you have to choose between an absolutely clear, unambiguous phrasing (as in the correct answer) and an objectively less clear phrasing, then, choose the clear and unambiguous one.