Answer : 1. "a"
Explanation :

When determining which article to use before a noun, consider the following:

• A is used before words that begin with a consonant sound.
• An is used before words that begin with a vowel sound.
• The is used when referring to specific or particular nouns.

In the sentence "He is _____ European," the word "European" begins with a consonant sound (/jʊəˈrəʊpɪən/), so the correct article to use is "a."

Therefore, the sentence should be: "He is a European."

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