Easy
Choose the word which is misspelt -
Explanation
Explanation
Check each word carefully: 'encourage', 'strange', and 'children' are all spelt correctly. But the correct spelling for the word meaning 'someone skilled in a field' is 'expert', not 'expart'. So the misspelt word is expart, option (2).
PRO TIP
Re-check your working by substituting the answer back into the original question.