Question 23: Mark the letter A, B, C, or D on your answer sheet to indicate the undelined part that needs correction in each of the following questions: deciding on the topic of the presentation, he started finding relevant information for it.
Knowledge of co-subject sentences
Having + Vpp, S+ V (past simple): after doing something, …..
=> The answer is A (Having deciding => Having decided)
After deciding on the topic of the presentation, he began to search for relevant information for it.