The correct passive form of the given sentence is:

☀ Ideas are generated by Group discussions.

Let's break down the options:

1. Ideas are generated by Group discussions. (Correct) This sentence correctly uses the passive voice and conveys the same meaning as the original sentence.

2. Ideas were generated by Group discussions. (Incorrect) This option uses the past tense "were generated," which suggests that the action happened in the past. The original sentence is in the present tense, so option 1 is more appropriate.

3. Ideas have been generated by Group discussions. (Incorrect) This option uses the present perfect tense "have been generated," which implies that the action started in the past and has relevance to the present. The original sentence is in the simple present tense, so option 1 better reflects the intended meaning.

4. Ideas had been generated by Group discussions. (Incorrect) This option uses the past perfect tense "had been generated," which implies that the action was completed before some other past event. The original sentence is in the simple present tense, so option 1 is the correct choice.