Which of the following is a good example of hterothallism?

Which of the following is a good example of heterothallism?

Which of the following is a good emitter

Which of the following is a good example of multiple allele-

Which of the following is a good example of multiple allele-

Which one of the following is a good example of 'scaffolding' (learning of a problem-solving task till the student is able to do it by herself)?