Why are EXCEL macros a security vulnerability? (Mark all correct answers) Because macros can be hidden hence users cannot see what they do. Because they can execute when the spreadsheet is opened before the user can intervene. Because macros are best suited to automating complex formulas and processes. Because users always have the option of not executing a macro; therefore, if users are unsure, they can merely ignore the macro Because macros cannot contain malicious code. Macros are not a security concern