Question

1. ¿de que nacionalidad — (ustedes)? sois eres son

Explanation:

The question is "¿De que nacionalidad ____ (ustedes)?" which is asking about the nationality of "ustedes" (you all, formal plural in Spanish). In Spanish, the verb "ser" (to be) for "ustedes" (plural formal) is "son". "Eres" is for "tú" (you, singular informal), and "sois" is for "vosotros" (you all, singular informal in Spain). So the correct verb form for "ustedes" is "son".

Answer:

A. Son (assuming the first option is labeled A, but based on the options given, the correct one is "Son" with its corresponding radio button)