As a project manager, Mary is managing 12 different projects. She realized something very interesting related to them. Sometimes they present some unique and particular rules, like the ones for projects #: 3, 6, and 8. She concluded that if either project 3 or project 6 is selected, then project 8 must be selected. For integer programming problems, which one of the alternatives listed below correctly models this situation? x3 + x6 + x8 1 x3-x8 1, x6-x8 1 x3 + x8 1, x6 + x8 1 x6 x8, x3 x8 None of the above