Circadian rhythm refers to
a) the pattern of emotional ups and downs we routinely experience.
b) a pattern of biological functioning that occurs on a 24-hour cycle.
c) the experience of sleep apnea following paradoxical sleep.
d) the cycle of four distinct stages that we experience during a normal night's sleep

The correct option is B) a pattern of biological functioning that occurs on a 24-hour cycle.

Explanation:

Biological rhythm is defined as the regular variation of an organic function related to the course of time, circadian biological phenomena (around the day), are those with a period of approximately 24 hours.

Circadian rhythms are physical, mental and behavioral changes that follow a daily cycle (the biological rhythm), and that respond primarily to light and darkness in an organism's environment. This cycle close to 24 hours, allows to recognize the sleep-wake phenomena and their homeostatic action, in the systemic processes of every living being. The circadian system is composed of photoreceptors, pacemakers and efferent pathways that allow a regular functioning of the sleep and wakeful state.

1. (1.2kw)x(15/60hours) = .3kwh --> a

2. (5kw)x(90/60hours)x(8cents/kwh) = $0.60 --> d

3. microwave --> 1200 watts = (1.2kw)x(6/60hours) = .12kwh

coffee-maker --> 900 watts = (.9kw)x(10/60hours) = .15kwh

therefore, it requires more energy for the coffee-maker to do the same amount of work.

so the answer is a.

answer; civil inattention;