The correct answer is B. Sensitive period
Explanation:
In development, the sensitive period refers to a lapse of time in which organisms are more susceptible or receptive to stimuli and therefore during this time there can be great advances in development. Additionally, different from critical periods sensitive periods do not imply irreversible consequence if the stimuli are not presented. For example, in human beings from birth to the age of 6 years, children are more receptive to learn and acquire certain skills such as learning a new language if exposed to it and therefore this can be considered as a sensitive period. Considering this, it can be concluded the definition presented refers to the Sensitive period.
arachnoid
a fine, delicate membrane, the middle one of the three membranes or meninges that surround the brain and spinal cord, situated between the dura mater and the pia mater.
