Many people that run, either to have a hobby or to stay fit,
is unaware that exercising in urban areas during peak traffic hours is unhealthy as doing so increases the intake of harmful gases.
A.
is unaware that exercising in urban areas during peak traffic hours is unhealthy as doing so
SV agreement problemB. are unaware that exercising in urban areas during peak traffic hours is unhealthy as
it "it" refers to "running" but we are talking about the entire act of running in urban areas during peak traffic hours. A pronoun can't stand for this act.C. are unaware that exercising in urban areas during peak traffic hours is unhealthy because
itSame as BD. are unaware that exercising in urban areas during peak traffic hours is unhealthy
and it"and" introduces another independent event, but here we have a reason for why a certain condition happens and hence need to use "because" or "as"E. are unaware that exercising in urban areas during peak traffic hours is unhealthy as doing so
Correct