Hey I really need some help I would appreciate it thank you !! Please answer if you are sure what the answer is this is important. Thanks again! Here are the answers to choose from

A. 18 cm
B. 15 cm
C. 14 cm
D. 8cm

Aiden drives to school and back each day. the school is 16 miles from his home. he averages 40 miles per hour on his way to school. if his trip takes 1 hour, at approximately what speed does aiden drive home?

Arley is building a model of a city map. in one part of the city, three roads form a right triangle, which harley draws as triangle abc, with the following measures: m∠b=90° and m∠a=30°. in his scale model, the hypotenuse of triangle abc, ac¯¯¯¯¯¯¯¯, has a length of 817−−√ cm. what is the value of a (the length of bc¯¯¯¯¯¯¯¯)?

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5