Which of the following is a substance that acts at a long distance from the site at which it is secreted? paracrine signal neurotransmitter hormone local regulator synaptic signal

The right option is; hormone

Hormone is a substance that acts at a long distance from the site at which it is secreted.

Hormones are chemical substances and special chemical messengers produced in the endocrine glands to maintain homeostasis, and to control most physiological activities, such as hunger/appetite, reproduction, emotions and mood.  When hormone-producing glands such as thymus or pancreas secretes hormones into fluids such as blood, the hormones will travel from the site at which it is secreted until it reach cells that will read the chemical as a message. Types of hormones include; cortisol, estrogen, testosterone, progesterone and melatonin.

answer: decrease

a limiting factor is the one which decrease the abundance, distribution and causes extinction of the population of species in a ecosystem. here, predators including hawks, owls and snakes are the limiting factor for the population of mexican free tailed bat.   although bats are nocturnal animals as they forge for food at night these predators also may remain active during night which can decrease the population of the mexican free-tailed bats. also, these bats eat only one type of insects that are moths. the food can also be a limiting factor as all 400 members are dependent upon same type of food needs that are moths. the decrease in the moth population can cause decrease in population size of the mexican free-tailed bats.

therefore, the scenarios will most likely to decrease the population size of the mexican free-tailed bats.  

yes it is weird but true