Which function is not continuous?

a. your altitude as a function of time while flying from reno to dallas?
b. time to travel from miami to pensacola as a function of driving speed?
c. number of tennis balls that can fit completely inside a particular box as a function of the radius of the tennis balls?
d. area of a circle as a function of radius.

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)

Cos^2x+cos^2(120°+x)+cos^2(120°-x)i need this asap. pls me

Atravel agent is booking a trip to england, scotland, ireland, and france for a group of senior citizens. the agent sent surveys to the group, asking which countries they would like to visit, in order, and created the shown preference schedule (e = england, i = ireland, s = scotland, f = france). which country is the condorcet winner? number of votes 15 12 16 19 1st f e e i 2nd e s i s 3rd s i s e 4th i f f f 1. scotland 2. england 3. france 4.ireland