"Append gap to previous track" is the correct way to rip tracks. An Audio CD has only a single continuous physical audio track. The individual logical tracks (aka "songs") are just indexes in a TOC. A CD player creates the individual logical tracks (songs) by interpreting the TOC data. A so galled gap is just the passage from a possibly existing INDEX 00 marker to the following INDEX 01 marker. When a gap is appended to the previous logical track, the INDEX 00 marker is ignored. Any decent ripper, including MC, rips the individual logical tacks from the INDEX 01 marker to the next INDEX 01 marker and ignores the INDEX 00 markers.
In the above picture the first line represents a CD that has four tracks.
The second line represents an otherwise identical CD, except that it has also INDEX 00 markers in its TOC.
A passage from an INDEX 00 marker to the following INDEX 01 marker can be silent or it can contain audio. A CD can have audibly silent "gaps" between the tracks without having any INDEX 00 markers. On the other hand a CD may contain a continuous mix and despite that have INDEX 00 markers. Technically the audio content on an Audio CD is completely separate from the TOC.