Final answer:
The correct subject/verb agreement for the sentence 'Sandria and her three friends _ to eat Mexican food' is 'love,' which makes option 3 the correct choice.
Step-by-step explanation:
The correct subject/verb agreement in this case is: Sandria and her three friends love to eat Mexican food. When the subject is a compound subject joined by and, a plural verb is used. This is because the compound subject (Sandria and her three friends) constitutes more than one person, which thereby requires a plural verb (love). Option 2 and option 4 are not correct because option 2 uses 'along with' which does not affect the verb's number, the correct verb is still plural, and option 4 suggests multiple answers are correct where only option 3 is actually correct.