Solution

The correct answer is option 2

Explanation:

L(r) = {a, aa, ab, aaa, aab, .... } This is a set of all strings starting with 'a'

L(s) = {aa, ab, aaa, aab, .... } This is a set of all strings starting with 'aa' or 'ab'

L(t) = {ab, aab, aaab, aaaab, ...} This a set of all strings starting with 'a', ending with 'b' and contains any number of 'a's in between them.

Therefore L(r) ⊇ L(s) ⊇ L(t)

Additional Information

* represents 0 or more number of symbols.

+ represents 1 or more number of symbols.