A split-second political calculation, maybe, or what the French call l’esprit d’escalier – “staircase wit,” or that perfect retort that popped into your head too late. In either case, Hillary Clinton now wonders what would have happened had she called out then-GOP candidate Donald Trump when he bizarrely stalked her on that debate stage last year.

Though she went high, Clinton, writing in  her new campaign memoir What Happened, had other options during the Oct. 10, 2016 televised debate. An exclusive excerpt of the audio book, read by Clinton herself, was unveiled on MSNBC’s Morning Joe today.

In the excerpt, Clinton notes that writing the book “wasn’t easy,” and that during the campaign she “couldn’t bear” the idea of letting down “millions of people – but I did.”

“I couldn’t get the job done,” Clinton narrates, “and I’ll have to live with that for the rest of my life.”

Here’s a partial transcript of the debate anecdote:

“This is not ok, I thought. It was the second presidential debate and Donald Trump was looming behind me. Two days before, the world heard him brag about groping women. Now we were on a small stage and no matter where I walked he followed me closely, staring at me, making faces. It was incredibly uncomfortable. He was literally breathing down my neck. My skin crawled. It was one of those moments where you wish you could hit pause, and ask everyone watching, “Well, what would you do?” Do you stay calm, keep smiling and carry on as if he weren’t repeatedly invading your space? Or do you turn, look him in the eye and say loudly and clearly, “Back up, you creep. Get away from me. I know you love to intimidate women but you can’t intimidate me. So back up.” I chose Option A. I kept my cool, aided by a lifetime of dealing with difficult men trying to throw me off. I did, however, grip the microphone extra hard.”

The “groping” comment references the immediately infamous Access Hollywood hot-mic recordings of Trump bragging to host Billy Bush about grabbing women by the genitals and getting away with it because he’s famous.

Clinton goes on to explain, and question, her own response to Trump’s weird stage antics. “I wonder though whether I should have chosen Option B? It certainly would have been better TV. Maybe I have over-learned the lesson of staying calm, biting my tongue, digging my fingernails into a clenched fist, smiling all the while, determined to present a composed face to the world.”

What Happened will be published on Sept. 12.

Here’s a tweet that links to the Morning Joe segment.