Which statement describes the appearance of a
temperature-vs.-time graph?

A horizontal line shows that the temperature
increases at a constant rate over time.

A vertical line shows that the temperature
decreases at a constant rate over time.

Horizontal lines where the temperature is
constant during phase changes connect
upward-sloping lines where the temperature
increases.

Horizontal lines where the temperature
increases are connected by upward-sloping
lines where the temperature is constant for
each phase.