Mai has recently created her own e-mail account. Her father gave her permission to e-mail her friends and family, but warned her that it is dangerous to open e-mails from people she does not know. Mai did not understand why her father would give her this warning. Why did Mai’s father say it is dangerous to open e-mails from unknown senders? Check all that apply. The sender could be a hacker. The e-mail could be inappropriate. The e-mails usually contain jokes. The e-mail may belong to someone else The message may contain a virus.