The end of days, or Armageddon, is known as 世界末日 (shìjiè mòrì) in Chinese. So, the correct answer is B.
The English word, “day,” is interpreted in Chinese as 天 (tiān), 日 (rì), or 节 (jié). For example, daytime — 白天 (báitiān); an important day — 重要的日子 (zhòngyào de rìzi); National Day — 国庆节 (guóqìng jié) and so on. So, what’s the difference between 天 (tiān), 日 (rì) and 节 (jié)?
1. 天 (tiān) is usually used to refer to the concept of time, for example 今天 (jīntiān) — today, 明天 (míngtiān) — tomorrow, 昨天 (zuótiān) — yesterday, 后天 (hòutiān) — the day after tomorrow. 天 (tiān) is also used in the names of the seasons, such as 冬天 (dōngtiān) — Winter, 夏天 (xiàtiān) — Summer, 春天 (chūntiān) — Spring and 秋天 (qiūtiān) — Autumn. Additionally, 天 (tiān) is used to refer to weather, for example “天变冷了。(Tiān biàn lěng le.)” which means the weather has gotten colder.
2. 节 (jié) is used in the names of holidays such as 圣诞节 (Shèngdàn jié) — Christmas day, 春节 (Chūnjié) — Spring Festival, 中秋节 (Zhōngqiū jié) — Mid-autumn festival, 清明节 (Qīngmíng jié) — Tomb-sweeping festival and 国际劳动节 (Guójì láodòng jié) — International Workers’ Day.
3. 日 (rì) is usually used for important dates or memorial dates, for example 生日 (shēngrì) — birthday and 纪念日 (jìniànrì) — memorial day.
Special attention should be given to the word 节日 (jiérì) which puts 节 (jié) and 日 (rì) together to form the word holiday.
Example:
Rénmen zhèngzài qìngzhù jiérì.
人们 正在 庆祝 节日。
People are celebrating the holidays.