The answer is 'although' because the question shows:
He can carry several bags of rice although he is a small man.(Dia boleh mengangkat beberapa guni beras walaupun dia kurus.)
And if the answer is 'because' it must sound like this:
He can carry several bags of rice because he is a fat man.(Dia boleh mengangkat beberapa guni beras kerana dia gemuk.
It's quite tough but if you understand the questions carefully and know the meaning and difference of the word although and because definitely you can answer it correct. Today also for me UPSR and I answered although because I know the meaning and difference of the word although and because. Anyway good luck for everyone who is sitting for UPSR tomorrow and Thursday, wishing all of you good luck and all the best. All my wishes are with you. Don't get stress but be calm even though the exam is hard read the questions twice and twice so that you will understand the question.