The word "frank" means being open, honest, and direct in speech. The best synonym for "frank" is candid. \n\n\\begin{itemize}\n \\item foolish: This is unrelated; "foolish" refers to lacking good sense, which is the opposite of being frank.\n \\item shameless: This means lacking shame, which is also unrelated to being frank.\n \\item wide spoken: This refers to something that is widely spoken, which is not synonymous with "frank."\n \\item candid: This is the correct choice as it also means being honest, straightforward, and open, which aligns perfectly with the meaning of "frank."\n\\end{itemize}\n\n\n\n \\boxed{\\text{candid}}