When a hormone is present at very low levels the number of t

When a hormone is present at very low levels, the number of target-cell receptors may increase. This is called: O Down regulation Paracrine Receptor recognition Up regulation Circulating hormone

The correct answer is Up Regulation, That is if a hormone is present at a low concentration , then the receptor increases in number so as to combat that low level of the hormone. THus his would be up regulation of the hormone