Self-study
It is widely believed that lancelets—small, primitive sea animals—do not have hearts. ████ ████████ ███ █ ███████████ ███████ ███ ████ ██████ ██ ██████████ ██ ██████ ██████ ████ █ ██████ ████████ ████ ██████ ██ ██████ █ ██████ █████ ████ ██ ████████ █████████ ███ █████████ ██ ███ █████ ██ ███████ █████ ███ ████████ █████████ ███ ████████ ████████████ ██ ███ ██████████ ██████ ███████ ████████ ███ ████████ ████████████ ██ █████ ████████ ███████
Summary
The author concludes that lancelets have hearts, because they have a vessel that is similar to other hearts in their structure and contractions.
Missing Connection
The conclusion is about having a heart, but we aren’t given information on what qualifies as having a heart. The support only comes from the structure and behavior of the lancelet’s vessel bearing similarity to other hearts. We can make the argument valid if we know for sure that one or both of these qualities (structure or behavior) having commonality with other hearts is enough to qualify as having a heart.
Analysis by TiaraLaulusa
24.
The argument's conclusion follows logically ██ █████ ███ ██ ███ █████████ ██ ████████
a
Only animals that ████ ███████████ ███████ ████ ███████
b
Some primitive animals █████ ████ █████████ ████ ████ ██ ██████ ████ ██ ██ █ ██████
c
A vessel whose █████████ ███ ███████ ███████ ████████ █████ ██ █████ ██████ ██████ ██ █ ██████
d
For a vessel ██ ██ ██████ ██ ██ ████████ ██████████ █ ██████ ████ ██████ ████ ███████ ████████ █████████████
e
No animal that ███ █ █████ █████ ██ ███████