The correct passive form of the given sentence is:

☀ The old man was laughed at by the boys.

Let's break down the options:

1. The old man was being laughed at by the boys. (Incorrect) This option uses the passive voice with the present participle "being laughed," which suggests an ongoing action. The original sentence is in the simple past tense, so option 2 is the correct choice.

2. The old man was laughed at by the boys. (Correct) This sentence correctly uses the passive voice and conveys the same meaning as the original sentence.

3. The old man was laughed by the boys. (Incorrect) This option changes the meaning slightly. It uses "laughed" without the preposition "at," making it sound as if the boys were doing the laughing themselves (i.e., actively laughing) rather than directing the laughter toward the old man.

4. The old man was being laughed by the boys. (Incorrect) This option has the same issue as option 1, using "being laughed" without the preposition "at." It also changes the meaning as described in option 3.