e.rb

require "pp"

data = "123. This is a question A Option One B Option two C Danke D Nope"
options = {}

("A".."D").to_a.reverse.each do |letter|
  data, letter, option = data.split(/ (#{letter}) (.+?)$/, 3)
  options[letter] = option
end

_, number, question = data.match(/^(\d+)\. (.+)$/).to_a

result = {
  number: number,
  question: question,
  options: options
}

pp result
# {:number=>"123",
#  :question=>"This is a question",
#  :options=>{"D"=>"Nope", "C"=>"Danke", "B"=>"Option two", "A"=>"Option One"}}