The answer is D (8 to 12)
While doing upper-body exercise routine, fatigue of target muscles can be safely achieved within<span> the short time-frame of about 1.5 minutes (the time-frame for anaerobic pathways) by simply performing 8 to 12 </span>repetitions<span> at a moderate movement speed.</span>
The anxiety levels will start to grow for them when they get much older
