These are cleft sentences where there is a separation the grammatical and the logical subject, and both make sense A1 and A2 and what they would be.

In A1 the verb agrees with the grammatical subject: The most important thing to me, singular.

In A2, the verb agrees with the logical subject: my friends (plural)

Is the odd one out is

A3 “The most important thing to me” as in A1 and A2 implies a single item or a single set of items?

What are the most important things that are important to you?

These are cleft sentences where there is a separation the grammatical and the logical subject, and both make sense A1 and A2 and what they would be.

In A1 the verb agrees with the grammatical subject: The most important thing to me, singular.

In A2, the verb agrees with the logical subject: my friends (plural)

Is the odd one out is

A3 “The most important thing to me” as in A1 and A2 implies a single item or a single set of items?

What are the most important things that are important to you?

These are cleft sentences where there is a separation the grammatical and the logical subject, and both make sense A1 and A2 and what they would be.

In A1 the verb agrees with the grammatical subject: The most important thing to me, singular.

In A2, the verb agrees with the logical subject: my friends (plural)

Is the odd one out is

A3 “The most important thing to me” as in A1 and A2 implies a single item or a single set of items?

What are the most important things that are important to you?

What

is shopping malls made of the action of passing time ( Oxford Dictionary)? Should I

go to the mall with a large group of people with no intention of buying anything? Urban Dictionary (MoP). Why not

on Facebook?

What

is shopping malls made of the action of passing time ( Oxford Dictionary)? Should I

go to the mall with a large group of people with no intention of buying anything? Urban Dictionary (MoP). Why not

on Facebook?