Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Q: Passage: The historian Frederick W. Mote wrote that the usage of the term 'social classes' for this system was misleading and that the position of people within the four-class system was not an indication of their actual social power and wealth, but just entailed 'degrees of privilege' to which they were entitled institutionally and legally, so a person's standing within the classes was not a guarantee of their standing, since there were rich and well socially standing Chinese while there were less rich Mongol and Semu than there were Mongol and Semu who lived in poverty and were ill treated. Question: What did Mote think the Yuan class system really represented?

A: degrees of privilege
****
Q: Passage: The most useful instrument for analyzing the performance of steam engines is the steam engine indicator. Early versions were in use by 1851, but the most successful indicator was developed for the high speed engine inventor and manufacturer Charles Porter by Charles Richard and exhibited at London Exhibition in 1862. The steam engine indicator traces on paper the pressure in the cylinder throughout the cycle, which can be used to spot various problems and calculate developed horsepower. It was routinely used by engineers, mechanics and insurance inspectors. The engine indicator can also be used on internal combustion engines. See image of indicator diagram below (in Types of motor units section). Question: Who developed a successful steam engine indicator for Charles Porter?

A: Charles Richard
****
Q: Passage: In 1891 Scottish chemist James Dewar was able to produce enough liquid oxygen to study. The first commercially viable process for producing liquid oxygen was independently developed in 1895 by German engineer Carl von Linde and British engineer William Hampson. Both men lowered the temperature of air until it liquefied and then distilled the component gases by boiling them off one at a time and capturing them. Later, in 1901, oxyacetylene welding was demonstrated for the first time by burning a mixture of acetylene and compressed O
2. This method of welding and cutting metal later became common. Question: What welding process was demonstrated in 1901?

A:
oxyacetylene welding
****