SCHEMA for SOAL:
id - bigint(20) unsigned
topik_id - bigint(20) unsigned
pertanyaan - text
opsi_a - varchar(255)
opsi_b - varchar(255)
opsi_c - varchar(255)
opsi_d - varchar(255)
jawaban - char(1)
created_at - timestamp
updated_at - timestamp
mode - enum('easy','expert')