instruction:
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
question:
Passage: Photo Gallery is an optional application to view, create and group photos from PS3, which is installed separately from the system software at 105 MB. It was introduced in system software version 2.60 and provides a range of tools for sorting through and displaying the system's pictures. The key feature of this application is that it can organize photos into groups according to various criteria. Notable categorizations are colors, ages, or facial expressions of the people in the photos. Slideshows can be viewed with the application, along with music and playlists. The software was updated with the release of system software version 3.40 allowing users to upload and browse photos on Facebook and Picasa.
answer:
What allows you to view photos on PS4?


question:
Passage: In the former Soviet Union, electric traction eventually became somewhat more energy-efficient than diesel. Partly due to inefficient generation of electricity in the USSR (only 20.8% thermal efficiency in 1950 vs. 36.2% in 1975), in 1950 diesel traction was about twice as energy efficient as electric traction (in terms of net tonne-km of freight per kg of fuel). But as efficiency of electricity generation (and thus of electric traction) improved, by about 1965 electric railways became more efficient than diesel. After the mid 1970s electrics used about 25% less fuel per ton-km. However diesels were mainly used on single track lines with a fair amount of traffic  so that the lower fuel consumption of electrics may be in part due to better operating conditions on electrified lines (such as double tracking) rather than inherent energy efficiency. Nevertheless, the cost of diesel fuel was about 1.5 times more (per unit of heat energy content) than that of the fuel used in electric power plants (that generated electricity), thus making electric railways even more energy-cost effective.
answer:
In the US, electric traction became more energy-efficient than what?


question:
Passage: In the 1960s, Downtown Houston consisted of a collection of mid-rise office structures. Downtown was on the threshold of an energy industry–led boom in 1970. A succession of skyscrapers were built throughout the 1970s—many by real estate developer Gerald D. Hines—culminating with Houston's tallest skyscraper, the 75-floor, 1,002-foot (305 m)-tall JPMorgan Chase Tower (formerly the Texas Commerce Tower), completed in 1982. It is the tallest structure in Texas, 15th tallest building in the United States, and the 85th tallest skyscraper in the world, based on highest architectural feature. In 1983, the 71-floor, 992-foot (302 m)-tall Wells Fargo Plaza (formerly Allied Bank Plaza) was completed, becoming the second-tallest building in Houston and Texas. Based on highest architectural feature, it is the 17th tallest in the United States and the 95th tallest in the world. In 2007, downtown Houston had over 43 million square feet (4,000,000 m²) of office space.
answer:

Texas consisted of what type of building in the 1960's?