Write SQL query to solve given problem: State the number of questions that were asked in the "mental health survey for 2018".. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT COUNT(T1.QuestionID) FROM Answer AS T1 INNER JOIN Survey AS T2 ON T1.SurveyID = T2.SurveyID WHERE T2.Description = 'mental health survey for 2018'