(There may be more than one)
The answer is F. CH3^+ has lost two electrons. That means that the ion will be planar with each H atom at the vertex of an equilateral triangle.
The species is called methyl carbocation. The 3 H-C-H bonds will be at an angle of 120 degrees.
All of the rest of the molecules/ions have bond angles that are not 120 degrees. See the link below for more information.
Hope this is helpful to you. JIL HIR