The reason that some individual hormones have so many different effects is that

The reason that some individual hormones have so many different effects is that
  a. they influence gene transcription.
  b. they trigger a second messenger system that produces a cascade of effects.
  c. there are a great many different cells in different tissues that have specific receptors for the
  hormone.
  d. the hormone is carried throughout the body and only a small amount is needed to produce
  its effect.
  e. they are realeased in different concentrations.

Question 2

Steroid hormones include
  a. estrogens.
  b. growth hormone.
  c. melatonin.
  d. thyroid hormone.
  e. oxytocin.