Step 1: Understanding the sentence.
The sentence describes an event where the manager has been accused of disloyalty to the company, but the focus is on the grammatical error in the phrase “the charges were subsequently drop.”
Step 2: Analyzing the error.
In the option “the charges were subsequently drop,” the verb “drop” should be in its past participle form “dropped” to maintain the correct grammatical structure. The correct sentence should be “the charges were subsequently dropped.”
Step 3: Conclusion.
Thus, the error lies in option (4), where “drop” should be “dropped.”