score:3
I believe that the exact options vary by country, and vary over time. However, for most people, what you'll want to do is head to the IHG Rewards Club Digital Rewards catalogue, then search for ebooks. When you're on there, pick all (no filters) pick to sort by price ascending, then check each first letter in turn. Actually, check the numeric first letters first, they often have the cheapest deals!
Right now, as a UK-based IHG member, in the ebooks section for books starting with the "letter" 0 (zero), I can see some 3 point options. I can confirm, from person experience, that buying one of these is enough to trigger the Accelerate task for a redemption. (Well, 2-3 weeks later, but then this is IHG with their very shonky IT systems...)