1. The correct answer is B. comparten.
Ellos, ellas, and Ustedes is the third person plural, which means that you need to use the appropriate form for that person, which in Spanish ends in -an, and -en. A is incorrect because it would be used with vosotros, C is incorrect because it would be used with el, ella, usted, and D would be used with nosotros.
2. The correct answer is A. earlier.
In Spanish speaking countries, such as Spain and many parts in South America, cena (which means dinner) is eaten at around 6-7, which is earlier than in the States where you have your dinner after 8 usually. It isn't necessarily healthier or heavier - it depends on the family.
3. The most common rice dish in the Spanish-speaking countries is C. arroz blanco.
That phrase means - white rice. Usually, white rice with no other condiments is eaten, mixed with other types of food. Arroz con leche is a type of pudding, arroz con pollo is rice with chicken, and quesú is another type of rice food, although it is not as common as arroz blanco.