I'm sort of torn between #6 & #7, so I checked both.
I lean toward 7 because I think that offering the different modes MAY create the notion that the mode is of great importance. The essential factors are that
A.) It is being done upon a personal, living, confession of faith in the saving power of Jesus, the Chosen One of the Father. (Only a person of age can make this type of confession.)
B.) The "applicant" ("baptizee") is aware that it is not a vehicle through with grace is imparted.
C.) The benefits of this simple act of obedience to the command of Jesus are conveyed and performed by God. (That is, it is not a "sacrament of the Church".)
However, in favor of #6, I would not want to deny an alternative mode to anyone, especially in the case of an elderly person with disabilities, primarily when the mode chosen by the congregation is immersion. (When I was a teen in our youth group, we had a youth weekend gathering in a neighboring state, and we were all housed in people's homes. I was put in an elderly woman's home, I spent a good bit of time talking with her. She had come into the MB circles from some group that did infant baptism, so she was not a member. It was not that she refused to be "rebaptized", but this was in the early 70's, she was up in years already, so had some physical limitations, but mostly it was the social factor - being seen soaking wet in front of a group of people. She had the old-time sensibilities. She asked if I thought it was OK to ask for a "private baptism". I do not recall for sure how I answered - I was probably around 16 or 17 at the time, but now I would say that I think this would be fine. Some say baptism is a public demonstration, a public testimony. Frankly, I have not found any support for that in Scripture. The only thing I see is the command to do it.)
Also as to giving options, I would discourage any notion that one mode is somehow "more Biblical" or "better, more effective", than any other. There are Scripture texts that tie the act of baptism to various types of symbolism - Death, Burial, & Resurrection (suggesting immersion), Sprinkling by the blood of sacrifice (suggesting sprinkling), and The Out-Pouring of the Spirit (suggesting pouring). [Maybe sprinkle some water on them, then pour water on them, then push them under?....
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As always, I am open to correction. I have never written out a statement like this before, so I may easily have missed some even more essential points, or I may also have erred in some of these I listed.
(I was baptized in a formerly "immersion only" group, the MB. Before around 1964 they would not accept the believer's baptism of anyone coming in from another Mennonite group UNLESS it had been by immersion. I was of course baptized after that, about 5 years after that change. They still did not allow any other options, just accepted other modes after the merger of the KMB conference with the larger MB conference.)