Choose the word that roughly means the same as the word highlighted in the…

In a synonym-matching question, a word must be matched by the exact sense it carries in that sentence's context, not just any dictionary meaning — many English words are polysemous, so the same spelling can function as one part of speech with one meaning in one context (e.g., a noun) and as another part of speech with a different meaning in another (e.g., an adjective).

Here, "current" modifies the noun "level", so it is functioning as an adjective meaning "existing or happening at this time; belonging to the present" — the sentence is saying the pollution level that exists right now is very high. "Present" carries exactly this adjective sense (as in "the present level", "the present situation"), so it is the option that means the same thing.

Each distractor substitutes a different sense or word class, not the one actually used in the sentence:

• "normal" denotes what is typical, standard, or expected — a level being current says nothing about whether it is standard, only that it holds right now.

• "usual" denotes what happens habitually or customarily over time — again a different axis from "existing at this moment".

• "electric" matches the NOUN sense of "current" (as in "electric current", a flow of charge) — a pollution level has no electrical-current meaning, so this picks the wrong word class entirely.

Since the sentence uses "current" as an adjective meaning "existing/happening now", and "present" is the option that carries exactly that adjective sense, "present" is the word that means the same as the highlighted word.