Looks like many introductory level courses like ECON 1, MATH 1A, CHEM 1A and 4A, and PHYSICS 7A have slightly below B averages (2.9xx). However, some other introductory level courses like COMPSCI 61A, ENGLISH R1A, PSYCH 1, UGBA 10, HISTORY 7A and 7B, SOCIOL 1 have higher averages in the B+ range. BIOLOGY 1A and 1B have lower averages in the B- range.
Of course, B or B- grades are not good for pre-meds, but this thread is about CS majors.