The witness will ______ what I have said.

Answer: 'bear out' — to confirm or support what someone has said.

Explanation: In the sentence, the intended meaning is that the witness will confirm or support the speaker's statement. Therefore, the correct phrasal verb is 'bear out'.

• bear out — correct choice; means to confirm or support (e.g., "The evidence bears out his claim").

• bear up — means to endure or remain strong under pressure; not used to mean 'confirm'.

• bear with — means to be patient with someone or something (e.g., "Bear with me"); does not mean 'confirm'.

• bear on — means to be relevant to or have bearing on an issue; it does not mean 'confirm'.

Example: "The witness will bear out what I have said," meaning the witness will confirm the speaker's statement.