There are two answers that depend on who’s writing you focus on. The two most influential Science Fiction writers of that time were HG Wells and Joules Verne.

HG Wells was a big marxist/socialist. His stories played on the ideas that mankind would ultimately resort to devouring itself – that the classes of “haves” and “have nots” would eventually develop into two different races of being, one feeding on the other. This was the idea behind his “Time Machine” story. It is also behind his “War of the Worlds” story.

Other writers, like Joules Verne and Conan Doyle wrote of mankinds “Pioneering Spirit and Invention”.

Joules Verne centered on “invention” and mankind’s “pioneering spirit” and fear of falling into the trap of “The Golden Age”. This was an idea at the time that man was reaching an age where there would be nothing left to discover. Verne played on how such thoughts would be mandkinds weakness to those who continued to advance (as in his book “20,000 leagues under the sea”). But he also focused on man’s ongoing pioneering spirit (as in “Around the World in 80 Days).

This was also echoed in Edgar Rice Bourroughs (The Land that Time Forgot) and Arthur Conan Doyle’s “Lost World”.

So the two major feelings are:
Empathy for the poor of the industrial revolution
and
Mankinds Pioneering and Inventive Spirit.

But if I had to pick one that was the “right answer” it would definately be “Pioneering and Invention”.

Though if you have a discussion on this during class, you could really score points with your professor if you pick up on the core issues of HG Wells if he thinks that Pioneering and Invention were the only main issues of science fiction during that time.