(A) potassium they contain
(B) bananas are slightly
(C) the natural
(D) radioactive due to

The following question gives a sentence which has been divided into four parts which may not be in their correct order of narrative. The sentence is then followed by five options, one of which gives the sequence of the rearranged parts to make the sentence meaningful. Choose the option which gives the correct sequence of the parts. If the sentence is already arranged in the correct sequence, mark option " No rearrangement required " as the answer.

The correct option is BDCA.

Let's logically re-order the given sentence fragments to form a grammatically correct and coherent sentence:

(A) potassium they contain
(B) bananas are slightly
(C) the natural
(D) radioactive due to

Step-by-step logical rearrangement:

1. Identify the subject/starting clause: Fragment (B) "bananas are slightly" introduces the subject ("bananas") and a verb with an adverb ("are slightly"), which requires an adjective to complete the predicate.

2. Find the predicate adjective: Fragment (D) "radioactive due to" provides the adjective ("radioactive") that logically modifies "bananas are slightly", followed by the preposition "due to". This gives the sequence B → D ("bananas are slightly radioactive due to").

3. Identify the object of the preposition: The phrase "due to" needs a noun phrase to explain the cause. Fragment (C) "the natural" acts as a modifier for a noun.

4. Complete the phrase with the noun: Fragment (A) "potassium they contain" supplies the noun "potassium" along with a relative clause "they contain". Placing (C) before (A) forms "the natural potassium they contain". This gives the sequence C → A.

Combining all the parts in order (B → D → C → A), we get the full meaningful sentence:
"Bananas are slightly radioactive due to the natural potassium they contain."

Therefore, the correct sequence is BDCA.