Do you know the Chinese pinyin of “老师?”

Beginner Level 初级 (chūjí)
“如果你想学好汉语，好的汉语老师是必不可少的.” The phrase “汉语老师” refers to Chinese teacher in English. Do you know the Chinese pinyin of “老师?”
A. Lăoshī
B. Làokē
C. Lăoshi
D. Lántiān