Amino acid sequences of cytochrome $c$ and ribulose $5$-phosphate epimerase from $40$ organisms were chosen and phylogenetic trees were obtained for each of these two protein families.

Determine the correctness or otherwise of the following Assertion [$a$] and the
Reason [$r$].

Assertion [$a$]: The two trees will not be identical

Reason [$r$]: The nature and frequency of mutations in the two families are different

1. Both [$a$] and [$r$] are true and [$r$] is the correct reason for [$a$]
2. Both [$a$] and [$r$] are true but [$r$] is not the correct reason for [$a$]
3. Both [$a$] and [$r$] are false
4. [$a$] is false but [$r$] is true.