Theory of Computation - Regular Languages

Consider the following two languages over the alphabet {a, b}: L₁ = { αβα |α ∈ {a,b}+ AND β∈ {a,b}+ } L₂ = {αβα|α ∈ {a}+ AND β∈ {a,b}+ } Which ONE of the following statements is CORRECT?

Let Σ = {a, b, c}. For x ∈ Σ*, and α ∈ Σ, let #α(x) denote the number of occurrences of α in x. Which one or more of the following option(s) define(s) regular language(s)?

Let $L_1, L_2$ be two regular languages and $L_3$ a language which is not regular. Which of the following statements is/are always TRUE?