The Yahoo property Verizon sold to SmugMug before reports it might sell Tumblr was Flickr.
Flickr is a photo- and video-hosting service that Yahoo acquired in 2005. When Verizon completed its acquisition of Yahoo in June 2017, Flickr became part of Verizon’s internet-media portfolio through Oath, the umbrella company that later became Verizon Media.
In April 2018, Verizon sold Flickr to SmugMug, a company known for photo hosting and photography services. The deal was part of Verizon’s broader reshaping of the former Yahoo properties. About a year later, reports said Verizon was considering selling Tumblr, creating a direct comparison between the two divestitures.
The other options do not fit this timeline. Yahoo Answers remained a question-and-answer service for much longer, Delicious was a social-bookmarking property, and GeoCities had been shut down by Yahoo in 2009. Tumblr itself was eventually sold in 2019, when Verizon Media transferred it to Automattic, the company behind WordPress.com.