Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

During the Minor Occultation (Ghaybat al-Sughrá), it is believed that al-Mahdi maintained contact with his followers via deputies (Arab. an-nuwāb al-arbaʻa or "the Four Leaders"). They represented him and acted as agents between him and his followers. Whenever the believers faced a problem, they would write their concerns and send them to his deputy. The deputy would ascertain his verdict, endorse it with his seal and signature and return it to the relevant parties. The deputies also collected zakat and khums on his behalf.
How did al-Mahdi maintain contact during his Occultation?