72. I have headache:

Explanation

The word "headache" is a countable noun, so it requires an article such as "a" or "an" when used in a sentence. "A" is used before words that begin with a consonant sound, and "an" is used before words that begin with a vowel sound. Since "headache" begins with a consonant sound (/h/), the correct article is "a." Therefore, the correct phrase is "I have a headache."