Which of the following is false with regard to prevalence ?
Prevalence:

Prevalence is defined as  "the total number of all individuals  who  have an attribute or disease at a  particular time  (or  during  a particular  period)  divided  by  the population at risk  of having the attribute or disease at this point in time or midway through the  period. 
Although referred to as a rate, prevalence rate is really a ratio. 
Prevalence is of two types : 

        (a) Point prevalence 
        (b) Period prevalence 

When  the  term  "prevalence  rate"  is  used,  without any  further  qualification,  it  is  taken  to  mean  "point prevalence".
It is a product of incidence and duration.
It can be determined by a cross-sectional studies.
It is a rate.
Prevalence is point prevalence unless otherwise specified.