Which relation is a function?

a.
(6, 5), (1, 1), (6, 4)

b.
(0, 1), (2, 3), (2, 5)

c.
(8, –2), (–2, 5), (6, 0)

d.
(–2, 3), (–5, 9), (–5, 3)

Acylinder and its dimensions are shown. which equation can be used to find v, the volume of the cylinder in cubic centimeters?

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?

Polygon abcde is reflected to produce polygon a′b′c′d′e′. what is the equation for the line of reflection?