<h2>Answer:</h2>
Option B is correct.
b. extending outward is more economical than extending upward
<h2>Explanation:</h2>
people tend to move from rural areas to urban for the greater facilities that they can enjoy at cities. This urban sprawl is also very economic because people will get more chances of jobs, business and work hence improving the economy.
Because they help regulate the marine environment.
C is the answer.
The temperature T<span> in degrees Celsius (°C) is equal to the temperature </span>T<span> in Kelvin (K) minus 273</span>°.
"The other halogens are not as electronegative and so other hydrogen halides cannot form hydrogen bonds between molecules. Only London Forces are formed. - Therefore more energy is required to break the intermolecular forces in HF than the other hydrogen halides and so it has a higher boiling point."
not a hack link, just stating where i got your answer from! -
https://www.mytutor.co.uk/answers/17558/A-Level/Chemistry/Explain-the-unusually-high-boiling-point-of-HF/
I'm not 100% sure but I'm leaning towards D. :)