Explanation:
To make a meaningful sentence, we need to rearrange the given parts in the correct order. Let's analyze each part of the sentence:

1. "of" - This is a preposition that indicates possession or relationship.

2. "we" - This is a pronoun that refers to a group of people including the speaker.

3. "heard" - This is a verb that means to perceive or receive information through the ears.

4. "him" - This is a pronoun that refers to a male person or object that has already been mentioned or is known.

5. "had" - This is a verb that indicates past possession or experience.

Now, let's look at the options:

a) 42351: This option suggests the order: "we heard had of him", which does not form a grammatically correct sentence.

b) 52341: This option suggests the order: "we had heard of him", which forms a grammatically correct sentence. However, it does not include the part "had" after "we".

c) 25341: This option suggests the order: "heard we had of him", which does not form a grammatically correct sentence.

d) 25431: This option suggests the order: "heard we had him", which does not form a grammatically correct sentence.

e) 25314: This option suggests the order: "heard we had him of", which does not form a grammatically correct sentence.

Therefore, the correct answer is option 'B' (52341), which rearranges the parts to form the sentence "We had heard of him."

Answer: B (52341)