Based on the description of the graph, in 1850:
- The population size was still relatively low and likely around 100 million, as it was stated that the population had reached 120 million by 1900 with slow growth before that.
- Steel consumption began around 1860, meaning that in 1850, steel consumption would have been at or near 0 million metric tons.
Using this information, the conclusion about steel consumption and population size in 1850 is:
The population was around 100 million and steel consumption began.