Determine the correctness or otherwise of the following Assertion [$a$] and the Reason [$r$].
Assertion [$a$]: Embryonic stem cells are suitable for developing knockout mice
Reason [$r$]: Homologous recombination is more frequent in embryonic stem cells than that in somatic cells
- Both [$a$] and [$r$] are false
- 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 [$a$]
- [$a$] is true. but [$r$] is false