“吨(dūn), ton” “斤(jīn), half kilogram or catty” and “克(kè), gram” are all units of weight.
“吨(dūn) is equivalent to 1,000 kilograms, which is usually used to measure the weight of heavy objects or large quantities of objects. Such as measuring the amount of concrete used to lay a foundation or the water your family consumes every month.
“克(kè)” is equivalent to 0.001 kilograms, which is often used to measure the weight of very light objects and usually the objects need to be measured accurately, like in chemical fields or gold markets.
“斤(jīn)” is equivalent to 0.5 kilograms, which is a commonly used unit of weight in Chinese people’s daily life, such as for weighing fish, meat, vegetables, fruits etc.
Zhè dài dàmǐ shíjīn.
这 袋 大米 十斤。
This bag of rice is ten-catty.
Wǒ zuótiān mǎi le sānjīn báicài.
我 昨天 买 了 三斤 白菜。
I bought three-catty of cabbages yesterday.
In our test, the customer wanted to buy some apples. And we know that fruits are usually sold by the catty in China. So “斤(jīn)” is the correct answer.