A conjunction combines or connects two sentences together. These parts of the resulting sentence are called clauses. When one clause is dependent on the other for its full meaning, it's called a subordinate clause, or the dependent clause. In the given sentence, the subordinate clause "listening to music" depends on the main clause "He worked on his accounts" for its full meaning. The given sentence is time-related, as it refers to two activities that take place at the same time. From the given options, 'while' is the most suitable conjunction, as it refers to an ongoing activity (listening to music) that takes place at the same time as the main activity (worked on accounts). Hence option D is correct. 'When' is a time-related conjunction, and refers to an activity as well, but in terms of interruption. 'When' is used when one activity causes an interruption in the other, or it begins a while after the main activity, hence it isn't used here and option A is incorrect. 'If' is a conjunction used in condition-related sentences, it refers to a condition, 'provided that', but here the main clause isn't based on any condition, hence option B is incorrect. 'That' is a conjunction used in purpose-related sentences, where the subordinate clause is the purpose or reason for which the main clause takes place, but here 'listening to music' is not a purpose, hence option C is incorrect.