<span>
C:horrified or shamed
</span>
The answer to your question is D.
If you write a sentence with an unclear antecedent, it means you used a pronoun that could refer to more than one person, place, or thing.
For example: I never go to that place because <u>they</u> have stale bread.
Who does <u>they</u> refer to? We don't know, it is unclear.
The glider.
-Makes use of gravity in order to stay on air.
-It is a heavier-than-air type.
-They move through the air in order to create the lift they need to stay on air.
-The major pioneer of this type of aircrafts was Otto Lilienthal.
-The first flight of a glider was achieved by Otto Lilienthal and Gustav Lilienthal in 1891.
-There exists different types of gliders: paragliders and hang gliders.
-They normally do not make use of any propulsion system (nonpowered).
-Were used during WWII for different purposes, such as providing goods or to study metheorology.
-Very popular for leisure time activities and sports.
-Paper airplanes are a very popular, commom and easy type of gliders, and a way to approach to their functioning.
