Determine the correctness or otherwise of the following Assertion [$a$] and the Reason [$r$].
Assertion [$a$]: Dam methylase protects $E$. coli $DNA$ from phage endonucleases
Reason [$r$]: $E$. coli Dam methylase methylates the adenosine residue in the sequence "$GATC$"
- Both [$a$] and [$r$] are true and [$r$] is the correct reason for [$a$]
- Both [$a$] and [$r$] are true but [$r$] is not the correct reason for [$a$]
- Both [$a$] and [$r$] are false
- [$a$] is false but [$r$] is true