The most important thing should be the Short Program with a Junior layout, as if the selected skater doesn't make the Free, only three or four JGP spots would be available for all Canadian Junior girls next season.
Megan has been doing really well as a Senior domestically, but at both of her international Junior assignments this season, she only scored in the mid-40s in the SP. I'd at least send her out to a Junior B to test her ability to deliver a clean-ish Short internationally before selecting her.
Lulu doesn't really have a 3Lo, and I don't think she'd make the Free with a 3T+3T, 2Lo and 2A layout.
Reese can score highly in the Short, but tends to struggle under pressure, so I feel like it would almost be mean to send her as the only entry and put her in a really high-pressure situation like this.
Victoria's overall maximum scoring potential is probably a little lower currently than the three girls I mentioned, but her lowest SP score of 52.something is much closer to the likely Free Skate cut-off and she's been somewhat more consistent than a lot of the other Junior girls.
Minsol would be the best choice - Consistent, with a great 3Lo and good PCS and she could earn herself a GP spot based on Season's Best score - but she'd have to be released and sent to an international competition for minimums really soon, and I don't see that happening