Need help with this Unix problem, there might be more than one answer.

Which of the following command(s) can be used to check if the string "aabbcc" matchesa pattern or not?

(a) expr "aabbcc" 'aa.*'

(b) echo "aabbcc" | grep 'aa.*'

(c) expr match "aabbcc" 'aa.*'

(d) egrep 'aa.*' << END

aabbcc

END