Sentence Correction (SC) | In January this year, a chemical used in the processing of coal leaked

Heysv2023 hope you are doing fine. I'm no expert but I am fairly confident that I can answer your question

Doubt #1: I'm afraid to say that interrupted and called are not modifiers but verbs
Doubt #2: Here too I'm afraid to say that this method of elimination is not the right way this is because used is a modifier not a verb. I presume eliminated it thinking that used is verb whereas called is modifier thus incorrect

To understand both your doubts let us understand the meaning of it.
Meaning:
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