Answer:
Incorrect usage of helping verb 'has' makes it sound ungrammatical or the wrong usage of the verb 'swam' with has.
"Jane swam the course several times." is the correct form or it can be
"Jane has swum the course several times".
Step-by-step explanation:
There is a grammatical flaw in the sentence due to the unnecessary usage of the helping verb 'has' which makes it superfluous. If the helping verb has to be remained intact then the past participle form of verb i.e. 'swum' should be used. Thus, there can be two possible answers as given above.