Step 1: Understanding the sentence meaning.
The sentence expresses that we are moving or drifting away from something — the “central idea.” Therefore, the correct word should indicate distance (literal or figurative).
Step 2: Analyzing the options.
- (a) farther: Means “at a greater distance,” either physically or metaphorically — correct usage.
- (b) either: Used for choice between two items — incorrect here.
- (c) neither: Negative form of “either” — incorrect meaning.
- (d) other: Means “different,” not suitable in this context.
Step 3: Grammar and usage.
“Farther” and “further” both can mean distance, but “farther” is typically used for physical or measurable distance, while “further” may be used for abstract distance (like “further discussion”).
Here, “getting farther away” clearly fits as we are moving away from the central point or idea.
Step 4: Constructing the correct sentence.
The correct sentence is: “We’re getting farther away from the central idea.”
Step 5: Conclusion.
Hence, the correct option is (a) farther.