The right answer is B.
Translation:
Lily: Nǐ zài gān shénme? Wǒ zhè jǐtiān dōu méiyǒu jiàn dào nǐ.
你 在 干 什么？ 我 这 几天 都 没有 见 到 你。
What are you doing? I haven’t seen you for several days.
Tom: Ài, wǒ zhè jǐtiān máng sǐ le.
唉，我 这 几天 忙 死 了。
Ah, I’m up to my neck in work.
Explanation:
In Chinese, 死 (sǐ) means to die or death. 忙死了 (máng sǐ le) is a widely used colloquial phrase to say that someone is extremely busy, or, busy to death. It should not be taken literally. Here 死 (sǐ) is an adverb used to modify the word 忙 (máng) and to intensify the degree of the tone. There are a lot of similar phrases in the Chinese language that use the character 死 (sǐ). For example: 笑死了 (xiào sǐ le) means laughing to death, and 累死了 (lèi sǐ le), means dead tired.
Examples:
1.Zǒu le zhème jiǔ, lèi sǐ le.
走 了 这么 久，累 死 了。
After walking such a long disance, I am dead tired.
2.Yào xiě zhème duō de lùnwén, máng sǐ le.
要 写 这么 多 的 论文，忙 死 了。
I’m up to my neck in papers.
Actually, 死 under these kinds of situation means deadly, not die.