To determine who ran 2.12 km in 45 minutes based on the graph, we need to analyze the plotted points for the participants.
The line for Bella passes through (45, 3.5), meaning Bella ran 3.5 km in 45 minutes.
The line for Ruby passes through (40, 2.5), meaning Ruby ran 2.5 km in 40 minutes.
The line for Greg passes through (45, 2.5), meaning Greg ran 2.5 km in 45 minutes.
The line for Paul passes through (25, 1), meaning Paul ran 1 km in 25 minutes.
Since none of the participants ran 2.12 km in 45 minutes, it appears there may be a misunderstanding in the question. However, if the focus is on who ran 2.5 km in the closest time to 45 minutes, the answer would be Greg.
Nevertheless, based solely on the given options and details about 2.12 km, none specifically corresponds.
If we have to choose based solely on performance at 45 minutes:
The closest participant running notably near to 45 minutes is Greg.
Therefore, the answer is Greg.