In the Romer Model,the Growth Rate of Ideas

In the Romer model,the growth rate of ideas,
,is increasing in:

A) the research share and the total population.
B) the knowledge efficiency parameter and the research share.
C) the knowledge efficiency parameter,the research share,and the total population.
D) the knowledge efficiency parameter and the saving rate.
E) the fraction of labor in research and development and the savings rate.