When to use IS vs ARE

English as a Second Language English Vocabulary, Grammar and Idioms
1

I need clarification on the proper use of the helping verb [IS]. It is my understanding that the subject/verb being plural should be proceeded with [ARE]. Thus, the sentence shown below should include the word [ARE] vs [IS].

Please respond with clear justification because I’m always in conflict with designers that submit these type of statments and generally challenge me when I question the validity of the grammer.

Is the question below grammatically correct?
1 - Which of the following statements is true?

Thank You

2

It should be “is” in this case because the subject is “which (one)”, not statements. " Which (ONE) is true (of the statements)?"