The question asks to rearrange the sentence, but the sentence provided in the prompt is already presented in one of the options. We must evaluate which of the arrangements is grammatically correct.
The sentence uses the subordinating conjunction 'Although' to connect two contrasting clauses: 'he was ill' and 'he went to work'.
(A) Although he was ill, he went to work. This structure is perfectly correct. It starts with a subordinate clause followed by a comma and then the main clause.
(B) He to work went, although he was ill. The word order to work went is incorrect in English. It should be went to work.
(C) He was although ill, he went to work. The placement of 'although' is incorrect. It should be at the beginning of its clause.
(D) He although was ill went to work. This sentence has incorrect word order and is ungrammatical.
The only logical and grammatically correct sentence is (A).