If you don't have Computing-12 and want to be safe, it is best to take CMPT 098 in 97-3 instead of CHEM 115. Going the ENSC 150 route will cause extra complications if you fail to get a B, since you will then get behind in the Computing sequence.
What this means is:
Those students who have taken this course as ENSC 493-3 in the past can also take ENSC 491-1 to "top up" the course to a full elective.